Replace homegrown Bitcoin RPC client with an off-the-shelf one

[delbonis]

The Bitcoin RPC client in the btcio module was copied in from previous prototypes. It functions for basic purposes well enough, but it's lacking numerous useful features and has some code quality issues (excessive allocation, ad-hoc encoding/decoding of values, etc.). We should replace it with an existing mature Bitcoin RPC client library that's tested and trusted by other projects, providing an impl for the L1Client trait that wraps it.

[voidash]

@delbonis i looked through https://github.com/sapio-lang/rust-bitcoincore-rpc-async. This is very close to the rust-bitcoincore-rpc project.
The discussion related to async version of bitcoincore-rpc on rust-bitcoin : rust-bitcoin/rust-bitcoincore-rpc#78

• I ran the integration test present there with v27.99 of bitcoind and only those related to legacy wallet failed.
• The latest commit was about 6 months ago
• This project seems to be used by nomic, sapio other than that i couldn't find alot of usage through github code search feature

this seems like a potential replacement. But maybe we may need our own fork like nomic has done to fit our needs.

[storopoli]

rust-bitcoind-json-rpc-client is being brought into the rust-bitcoin org: rust-bitcoin/rust-bitcoin#3225