Prompting the user to set Pixel/Quickstep as default Home app.

requestQuietMode API throws SecurityException in case its called
from a non-default Launcher app.
To mitigate this, we catch the exception and prompt the user
to set their default launcher to the current app.

Video(Pixel): https://photos.app.goo.gl/ni5X1c6vBbYW2JMJ9
Video(Pixel-aosp): https://photos.app.goo.gl/cYLJpTYW76Jnbonc9

Bug: 320446272
Test: Manual
Flag: NONE Bug fix tweak.
Change-Id: I6afb2ae85cabc038e1503e9c34eebd974c4f7a50