As a preparatory measure for using showXFilePicker, the Qt file
filter has to be transformed to the format used by the showXFilePicker
(sXFP) options. A class structure reflecting the options was created. Based on
an input in the form of a qt file filter, it will parse the filter to
the sXFP options format. Unit tests were added and the code is not yet
used in non-test env, next change will use it.
Task-number: QTBUG-99611
Change-Id: I277286467a7b5ce6f323c19bdd31740a41b6a6be
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>
Mikolaj Boc