> util: Add GetPathArg default path argument
>
> Let GetPathArg method be used more places for path arguments that have
> default values, like "-settings" and BITCOIN_SETTINGS_FILENAME in the
> next commit.
>
> Also:
>
> - Fix negated argument handling. Return path{} not path{"0"} when path
> argument is negated.
>
> - Add new tests for default and negated cases
>
> - Move GetPathArg() method declaration next to GetArg() declarations.
> The two methods are close substitutes for each other, so this should
> help keep them consistent and make them more discoverable.
> util, refactor: Use GetPathArg to read "-settings" value
>
> Take advantage of GetPathArg to simplify code slightly.
The change to check-doc is necessary for linting.
> Use GetPathArg where possible
>
> Co-authored-by: Hennadii Stepanov <32963518+hebasto@users.noreply.github.com>
This is a backport of core#24306
Depends on D15063