Show a toast for background activity starts but only abort the start
if the feature is enabled (it's disabled by default)

The idea is to provide feedback for dogfooders and 1P app devs to
file bugs for us to investigate.

Former behaviour:
feature off (default) - do nothing, exit early
feature on - log to logcat and TRON, show the toast, and abort start

New bahaviour (temporary permissive mode):
feature off (default) - log to logcat and TRON, show the toast, and
                        allow start anyway
feature on - log to logcat and TRON, show the toast, and abort start

Bug: 110956953
Test: atest WmTests:ActivityStarterTests
Test: manual, both on and off
Change-Id: If11447c709deba1f25616e2bf8c14175d55cb1d5
2 files changed