Favorites improvements

[mmathieum]

As a user I want easier favorite management

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• [ ] when adding a new favorite, add to (default) folder and show/snack-bar toast to suggest changing folder
• [ ] replace favorites folders management dialog by a bottom sheet
  • List of existing folders + new folder edit text + remove favorite button (+cancel button)
• [ ] (?) allow to use an emoji (:house: :office: ...) to replace favorite folder icon, show emoji instead of :star:
  • Use an Emoji font (downloadable fonts) (AndroidX Emoji)