dfx, agent, and related issues

[bdemann]

Below are a few issues azle has that are caused by issues on dfinity's side of things. They are collected here for convenience.

• Unify vec{null} length limit on canister and client side as per https://forum.dfinity.org/t/regression-with-vec-of-null-in-rust/25505/5
• Alphabetically ordered Service properties https://forum.dfinity.org/t/services-wont-deserialize-properly-if-functions-arent-in-alphabetical-order/20885 (Verify fix in agent 0.20)
• DFX CLI requires variant to have at least one field while the spec doesn't specify that
• Inconsistent behavior of empty tuples (returned as {}, expected to be passed as parameters as [])
• Problems with IDL.Rec() as per https://forum.dfinity.org/t/agent-js-problems-with-recursion-and-blobs/25737
• LookupPathAbsent https://forum.dfinity.org/t/lookuppathabsent/23461
  • See also Fix http_counter example #1326
• Infinity and NaN can be represented by the agent but not textually in the cli Support parsing inf/nan for float type dfinity/candid#499

Not sure
- [ ] #1511 (Needs better reproduction of the error)