android: MainActivity overhaul

This moves several parts of the main activity into fragments that manage themselves to react to changes. UI changes like the appearance of a new search view or when the games list changes now gets updated via multiple view models. This also starts a conversion to the androidx navigation component which furthers the goals mentioned previously with more fragment responsibility. This will eventually allow us to use one activity with interchanging fragments and multiple view models that are stored within that central activity.

fdas