Launch theme chooser that supports cyngn.intent.category.APP_THEMES

If we receive an ActivityNotFound exception we will simply show
the theme settings fragment.

Change-Id: I38bf6857125cdeda310e3bb5614fd6adaba8265f
Settings: Minor string update for msim

Change-Id: I20edc79b291405b44cbf483f615c6473e5934de8