Improvements for pagination editor

[solth]

Description

As described in #6359 the usability of the pagination editor could be improved by adjusting various aspects of it (taken from the discussion mentioned above):

• remove page selection - not required anymore once multiselection in the structure tree is enabled by Drag & drop multiple tree nodes in structure tree #6340
• realign pagination editor fields from lines into grid to make better use of available space
• add option to show logical pagination in gallery
• add alphabetic pagination type (Metadata-Editor: Pagination Option -> Alphabetic #6279)
• paginate pages in selected structure (Option to remove/add pagination of an element #5986) - this should probably be implemented as a way to select all pages of a structure element via a new context menu option and then apply a pagination to the selected pages
• save default pagination type in user settings (Default pagination type in user settings #6045)
• add link to advanced pagination documentation in Github wiki
• rename button "Cancel" to "Reset" or some other more appropriate label
• add option to switch order of "Recto/Verso" pagination (Metadata-Editor: sheetpagination starting with Verso-Pages #6270)
• dynamically adjust available options depending on selected pagination type (for example hide "start value" and other additional options when selecting "uncounted")

@subhhwendt & @SonjaGellert please add further points were needed!

Related Issues

#5986
#6045
#6270
#6279

Expected Benefits of this Development

Improve usability of pagination editor.

Estimated Costs and Complexity

• medium ~ less than 10 working days