rpc: Avoid initialization-order-fiasco on static CRPCCommand tables
Summary:
Currently the fiasco is only theoretical because all content of the table are compile-time constants. However, the fiasco materializes should they ever become run-time constants (e.g. #18531).
Backport of core PR18532.
Depends on D8553.
Test Plan:
ninja all check-all
Reviewers: #bitcoin_abc, deadalnix
Reviewed By: #bitcoin_abc, deadalnix
Differential Revision: https://reviews.bitcoinabc.org/D8567