Remove OpenSans fonts from maui-mobile template

### Description

The default templates ship with two OpenSans fonts embedded. I'd suggest you remove these, since they require app publishers to include the Google license for these apache-licensed fonts. It seems like these are more there to show embedded fonts can be done, rather than actually being helpful as a starter template (in general I wish the template got slimmed more down and the dotnet bot svg and anything else you won't be shipping/replacing gets removed too).

### Public API Changes

None

### Intended Use-Case

Starter template shouldn't require user to understand licensing requirements for embedded content.
It also seems like a bit much to include two fonts, just to be used by a few of the styles.