Add support for themed icons

[Rycoh99]

Is your feature request related to a problem? Please describe.
No

Describe the solution you'd like
I'd love to see support for themed icons, this would make the app feel more integrated with the user's customizations, providing a consistent look

Describe alternatives you've considered
Using apps that create "pinned" shortcuts to other apps in order to set custom icons (on system launchers which don't have support for icon packs), however, this is not very practical.

Additional context
The documentation for adaptive icons: https://developer.android.com/develop/ui/views/launch/icon_design_adaptive

[nicorac]

I have near to no experience with this topic and I'm not a graphic designer (at all 😉), but I’ll take a look at the documentation to get a bit more familiar with it.
In the meantime, if you (or anyone else) would like to share your own version of the icons, feel free to post them here (or in a pull request).

[Rycoh99]

As I can't figure out how to recompile the app from the source, nor being familiar with the codebase of BCR-GUI (I don't have much experience with developing Android apps either), I managed to do it myself using apktool, the steps I have done are:

1. Inside res/drawable I created a new file, ic_launcher_monochrome.xml
2. Inside res/mipmap-anydpi-v26 I replaced both "ic_launcher.xml" and "ic_launcher_round.xml" with the contents of ic_launcher__and__ic_launcher_round.xml
3. Rebuilt the apk
4. Themed icons now work, while also keeping non-themed icon intact