Package phosh-osk-stub: Information

Phosh OSK Stub in an experimental keyboard for quick prototyping and to
debug input related issues in phosh.

For a production ready on-screen keyboard see squeekboard.

The purpose of phosh-osk-stub:
- allow experimentation without the risk of breaking end user systems
- be helpful when debugging input-method related issues
- be quick and easy to (cross)compile
- allow to move GObject bits and Widgets over to squeekboard easily if
  desired (hence provide API documentation)