Bundle Ubuntu font resource instead of using as downloadable font

[jkuester]

Splitting this change out from #240.

Simply bundles the actual Ubuntu font .ttf instead of referencing Ubuntu as a downloadable font.

As a bit of history, Slim-Launcher previously bundled the Ubuntu .ttf files before switching to the downloadable font format. However, downloadable fonts require a font provider to be available in Android.

A device must have Google Play services version 11 or higher to use the Google Fonts provider.

Now, in my experience, many Android distros (e.g. LineageOS and GrapheneOS) seem to work around this somehow (perhaps by implementing their own fonts provider). I have run Unlauncher successfully on many instances of LineageOS and GrapheneOS without Google Play Services and have never seen font issues. 🤔 Be that as it may, the other downside of using downloadable fonts is that the Google fonts provider (and probably other implementations) will load the fonts from fonts.google.com which may not be reachable in some locations/environments. (E.g. someone may block their device from accessing any google.com domains.)

I think bundling the .ttf for the default typeface makes sense in this case since since it is fundamental to the look/feel of Unlauncher and should not be dependent on access/availability of an external service/domain.