BlenderKit: improve right click menu

-basically a complete revamp of the code, enables to display asset information in a much cleaner way with more tooltips e.t.c.
-simplified floating asset preview - name needs to be fixed still, and tooltip generation cleaned
-added several new icons, deleted one unused
-improve a lot of tooltips
-fix rerender of thumbnails in unsaved files (would save assets into addon directory)
-reorganize some rating functions into ratings_utils.py
-new 'wrap' operator for web links, allows to have custom tooltips for each link