c8e6771af0 test: restrict multiple CLI arguments (naiyoma)
8838c4f171 common/args.h: automate check for multiple cli commands (naiyoma)
Pull request description:
This PR is a continuation of the validation suggested [here](https://github.com/bitcoin/bitcoin/pull/27815) to ensure that only one Request Handler can be specified at a time.
ACKs for top commit:
stratospher:
reACK c8e6771.
achow101:
ACK c8e6771af0
tdb3:
cr re ACK c8e6771af0
Tree-SHA512: f4fe036fee342a54f1a7ac702ac35c40bf3d420fde6ab16313a75327292d5ee5c8ece1be9f852a13fcf73da1148b143b37b4894e294052abdde6eefb2e8c6f3f