Keyboard shortcut to go to the homepage from a video

**Is your feature request related to a usage problem (not a bug)? Please describe.**
I can manage pretty much all the UI with a combination of tab for picking videos and shortcuts for playback and fullscreen/subtitles, but I can't exit a video and go back to the home page without closing and reopening the app

**Describe the solution you'd like to see implemented**
I would hope to have keyboard shortcuts to go to subscriptions/playlists

**Describe alternatives you've considered**
An alternative would be something like hint mode from vim-inspired browsers and browser extensions (qutebrowser and tridactyl/vimperator, respectively)

**Screenshots**
**Additional context**

No files, tests, or entry points are named. First clarify which destinations and key bindings are required, then inspect the existing video-view shortcut and navigation behavior. Done should include working shortcuts that return from a video to the requested subscriptions or playlists views.

Written by the indexing model from the issue text.