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