Break builder pattern to expose all setters via bindings

[tnull]

Closes #65

Unfortunately there is no good way of exposing the builder pattern via Uniffi bindings currently. We therefore resort to internal mutability and using setters on the Builder object.

[tnull]

Rebased on main.

[tnull]

Rebased on main after #70 has landed. We now also expose the RGS setter methods via bindings.

Moreover, since we already have EntropySourceConfig and GossipSourceConfig, I now moved the Esplora server URL to a corresponding enum ChainDataSourceConfig, which will us to add further variants (e.g., Electrum) in the future without breaking the API.

Additionally, we document the set defaults and switch our default config to Network::Bitcoin while we're here.

[tnull]

Rebased after #85 landed.

[tnull]

Rebased on main after #101 landed.

[tnull]

I now included another commit that moves all UniFFI-specific types and trait impls to a dedicated module, which is now feature-gated behind the uniffi feature. There are three main motivations to do this:

1. decluttering the codebase, in particular as types.rs started to get unwieldy
2. UniFFI pulls in additional dependencies which Rust users don't have to put up with if they don't use it anyways and
3. It may allow us to have a saner MSRV for the Rust part in the future, as UniFFI currently requires something like 1.62.0.

However, I'll look into actually lowering the MSRV separately, as it may require downgrading UniFFI, and IIRC there was good reason why I had upgraded to 0.23.0 in the first place...

[jkczyz]

Looks good minus a couple easy comments.

[tnull]

Updated the commits to address feedback and included:

diff --git a/src/lib.rs b/src/lib.rs
index b9b75ca..3a0526f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -375,22 +375,18 @@ impl Builder {

                // Initialize the on-chain wallet and chain access
-               let seed_bytes = if let Some(entropy_source_config) =
-                       &*self.entropy_source_config.read().unwrap()
-               {
-                       // Use the configured entropy source, if the user set one.
-                       match entropy_source_config {
-                               EntropySourceConfig::SeedBytes(bytes) => bytes.clone(),
-                               EntropySourceConfig::SeedFile(seed_path) => {
-                                       io::utils::read_or_generate_seed_file(seed_path)
-                               }
-                               EntropySourceConfig::Bip39Mnemonic { mnemonic, passphrase } => match passphrase {
-                                       Some(passphrase) => mnemonic.to_seed(passphrase),
-                                       None => mnemonic.to_seed(""),
-                               },
+               let seed_bytes = match &*self.entropy_source_config.read().unwrap() {
+                       Some(EntropySourceConfig::SeedBytes(bytes)) => bytes.clone(),
+                       Some(EntropySourceConfig::SeedFile(seed_path)) => {
+                               io::utils::read_or_generate_seed_file(seed_path)
+                       }
+                       Some(EntropySourceConfig::Bip39Mnemonic { mnemonic, passphrase }) => match passphrase {
+                               Some(passphrase) => mnemonic.to_seed(passphrase),
+                               None => mnemonic.to_seed(""),
+                       },
+                       None => {
+                               // Default to read or generate from the default location generate a seed file.
+                               let seed_path = format!("{}/keys_seed", config.storage_dir_path);
+                               io::utils::read_or_generate_seed_file(&seed_path)
                        }
-               } else {
-                       // Default to read or generate from the default location generate a seed file.
-                       let seed_path = format!("{}/keys_seed", config.storage_dir_path);
-                       io::utils::read_or_generate_seed_file(&seed_path)
                };

@@ -417,27 +413,22 @@ impl Builder {
                .expect("Failed to set up on-chain wallet");

-               let (blockchain, tx_sync) = if let Some(chain_data_source_config) =
-                       &*self.chain_data_source_config.read().unwrap()
-               {
-                       match chain_data_source_config {
-                               ChainDataSourceConfig::Esplora(server_url) => {
-                                       let tx_sync =
-                                               Arc::new(EsploraSyncClient::new(server_url.clone(), Arc::clone(&logger)));
-                                       let blockchain = EsploraBlockchain::from_client(
-                                               tx_sync.client().clone(),
-                                               BDK_CLIENT_STOP_GAP,
-                                       )
-                                       .with_concurrency(BDK_CLIENT_CONCURRENCY);
-                                       (blockchain, tx_sync)
-                               }
+               let (blockchain, tx_sync) = match &*self.chain_data_source_config.read().unwrap() {
+                       Some(ChainDataSourceConfig::Esplora(server_url)) => {
+                               let tx_sync =
+                                       Arc::new(EsploraSyncClient::new(server_url.clone(), Arc::clone(&logger)));
+                               let blockchain =
+                                       EsploraBlockchain::from_client(tx_sync.client().clone(), BDK_CLIENT_STOP_GAP)
+                                               .with_concurrency(BDK_CLIENT_CONCURRENCY);
+                               (blockchain, tx_sync)
+                       }
+                       None => {
+                               // Default to Esplora client.
+                               let server_url = DEFAULT_ESPLORA_SERVER_URL.to_string();
+                               let tx_sync = Arc::new(EsploraSyncClient::new(server_url, Arc::clone(&logger)));
+                               let blockchain =
+                                       EsploraBlockchain::from_client(tx_sync.client().clone(), BDK_CLIENT_STOP_GAP)
+                                               .with_concurrency(BDK_CLIENT_CONCURRENCY);
+                               (blockchain, tx_sync)
                        }
-               } else {
-                       // Default to Esplora client with blockstream endpoint.
-                       let server_url = DEFAULT_ESPLORA_SERVER_URL.to_string();
-                       let tx_sync = Arc::new(EsploraSyncClient::new(server_url, Arc::clone(&logger)));
-                       let blockchain =
-                               EsploraBlockchain::from_client(tx_sync.client().clone(), BDK_CLIENT_STOP_GAP)
-                                       .with_concurrency(BDK_CLIENT_CONCURRENCY);
-                       (blockchain, tx_sync)
                };