DeskClock: Digital widget: Redesign

* Redesign the widget in terms of font, separator, spacing and colors
* Provide separate theming for light and dark wallpapers - that way
  it's easier visible on various backgrounds
* Provide an additional layout with a solid background - it also changes
  depending on the chosen wallpaper!
* Let the user decide on insert, if transparent or solid should be used
  -> provide a configuration activity

TBD (separate patch):
* Landscape layout for widget and config activity

Co-authored-by: Asher Simonds <dayanhammer@gmail.com>
Change-Id: I4bab4ce31630e6d2a5a1c857db9a76356f66e0ce