OpenXML Filter UI: develop Rainbow UI for the font mapping

As support for the font mapping in DOCX, PPTX and XLSX documents was introduced in the scope of corresponding issues ~~#937~~, ~~#958~~ and ~~#972~~, it would be reasonable to provide the UI part for that feature as well.

Hint: the implementation can be made on top of the solution for issue ~~#1147~~. Please search for the ResponsiveTable interface for more details.