getcommitment output as hex vs. bytes + draft setptr subcommand

[spacesops]

Make it easier to compare space-cli getcommitment to subs cert verify.

[spacesops]

Also adding a draft implementation of the setptr subcommand. The intent is to provide a way to set the data bytes of a script_pubkey controlling a ptr of a subspace name like name@space. This is similar to setrawfallback to set the data of a top-level space but at the subspace level.

How the eventual tx gets signed is currently at issue. An attempt was made to pass the private key (from subs request) to the subcommand. This is quite insecure, but useful for testing. This is the current output.

spaces:~/git/spaced-spacesops$ spaces setptr --prv 241e...ac27 -f 10 sptr14frcy...d5nz abcdef
⚠️ setptr: Private key signing not yet implemented - requires keypair validation and transaction signing

Ideally the createptr and setptr (and getptr) functions would be executed from a funded wallet that the subspace owner would use apart from the operator's involvement.