refactor: Run type check against RPCArgs (1/2)
Summary:
It seems brittle to require RPCTypeCheck being called inside the code logic. Without compile-time enforcement this will lead to places where it is forgotten and thus to inconsistencies and bugs. Fix this by removing the calls to RPCTypeCheck and doing the check internally.
Backport of core#26039.
Depends on D16253.
Test Plan:
ninja all check-all
Reviewers: #bitcoin_abc, PiRK
Reviewed By: #bitcoin_abc, PiRK
Differential Revision: https://reviews.bitcoinabc.org/D16254