> qt: Add a function that extracts the suffix from a filter
>
> Extract the 'Extract first suffix from filter pattern...'
> functionality into a testable utility function
> qt: Replace `QRegExp` with `QRegularExpression`
>
> Co-authored-by: Pavol Rusnak <pavol@rusnak.io>
> Co-authored-by: Jarol Rodriguez <jarolrod@tutanota.com>
> test, qt: Add tests for `GUIUtil::extractFirstSuffixFromFilter`
This is a backport of core-gui#620
Depends on D18177