This allows the constructor to ask the rpc manager for the name of the
rpc method or the rpc argument names instead of having it manually
passed in.
Note: added underscores to some constructors' arguments to prevent shadowing fields, like previously done in D5906
This is a backport of [[https://github.com/bitcoin/bitcoin/pull/19386 | core#19386]] [2/5]
https://github.com/bitcoin/bitcoin/pull/19386/commits/faaeb2b0b347b40ce456a951eec5e820587e5b02