Allow using wxTextMeasure::GetLargestStringExtent() with wxArrayString.

Allow using wxTextMeasure::GetLargestStringExtent() with wxArrayString.

Change the signature of this method to take the number of strings and the
pointer to the first of them instead of wxVector<wxString> as this allows it
to be used with all of wxVector<wxString>, wxArrayString and raw arrays of
wxStrings.

Also return the computed size from it instead of filling output parameters.

Closes #14781.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72802 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775