rpc: Assert that RPCArg names are equal to CRPCCommand ones (rpcdump)

Summary:
This concludes backport of core#19717 [4/4]
https://github.com/bitcoin/bitcoin/pull/19717/commits/fa3d9ce3254882c545d700990fe8e9a678f31eed

Depends on D10147, D10149 and D10159

Note: the forward declaration of RPC functions in rpcwallet.cpp don't seem to exist in Bitcoin ABC, and the ones in wallet_tests.cpp were in rpcdump.h (see D45)

Test Plan: ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D10148