Capability to display sideloaded apks

[kevin-schmid]

Hello!

I really like your fine and minimalistic launcher! The only thing I'm really missing is the capability to display sideloaded apps like F-Droid and apps that are installed through it. So I went ahead and implemented it. I haven't tested it on my TV as of yet, but it seems to work on the emulator. Maybe you find the time to check my PR. #3

[hugegreenbug]

Thank you. I will review it soon.