homescreen: Implement ocean mockups, rework layout

This commit does some reworking of the homescreen layout, following designs from the ocean v3 mockups.

Key changes:

• Add glide animation when the homescreen is focused/unfocused (ex. app opens)
• The top left header now consists of a digital clock, that shrinks as the user scrolls down in the view
• All homescreen actions have been shifted together to the top right
• The background darkens as you scroll down for users to focus on the content
• Removed the clock applet (since the digital clock is now here)
• Combined the user and shutdown actions together to just prompt the full system actions screen
• Fixed some issues with key navigation when different rows don't exist
• Removed category header backgrounds, now that there is contrast with the background
• Use Breeze Dark as the default color scheme, since most TV UIs are dark