[LINTER] Integrate check-rpc-mappings to arcanist

Summary:
Make the check-rpc-mappings.py linter run with arc lint. This is a
global linter so it will run only once.

Test Plan:
Should return no error:

arc lint --everything

Remove the line {"getblock", 1, "verbosity"}, from the table
vRPCConvertParams[] in src/rpc/client.cpp then run

arc lint

Check the linter returns both an error and a warning message.

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D3752