[avalanche] Optionally select a proof id in the getavalanchepeerinfo RPC

Summary: This changes the behavior of the RPC so only the peer associated with this proof id is returned. This is an optional parameter, there is no change in behavior by default.

Test Plan:

./test/functional/test_runner.py abc_rpc_getavalanchepeerinfo

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D11141