Remove outdated qualifiers on resources folders

[MGaetan89]

Some resources were still in the -v21/-v22/-v23 resources folders.
This PR moves them to the main folder, updating the original files when needed.

[nift4]

shouldn't this also remove .png files for example in ui library? while the .png files would still be used on devices that exactly match the standard dpi qualifiers, anydpi .xml files will be used for any other dpi, and frankly there is no reason to keep the app size bloat that are these .png files anymore as anydpi vector drawables work just fine for these.

[MGaetan89]

Good point! I'll look into removing the PNG files when there is a vector equivalent

[tonihei]

shouldn't this also remove .png files for example in ui library

Yes, it should, thanks for noting! These pngs only existed to support API<21 devices, so can now be removed entirely.

[MGaetan89]

Done. I've removed PNG files that already have a vector equivalent in a0d7ba3, and converted exo_icon_circular_play to vector in c00d28f.

Note

There's still exo_icon_vr.png in :lib-ui that is not a vector, but I didn't find the icon on https://fonts.google.com/icons