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 (closed), #958 (closed) and #972 (closed), 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 (closed). Please search for the ResponsiveTable interface for more details.