FGS background start restriction.

1. Background started foreground service shall not have
while-in-use permissions including location, camera and
microphone. Many exemptions have been applied including:
--FGS started by widget.
--FGS started by notification.
--FGS started by IME or other visible app.
--FGS started by ROOT_UID, SYSTEM_UID, NFC_UID.

2. Add a phenotype key KEY_DEFAULT_BACKGROUND_FGS_STARTS_RESTRICTION_ENABLED
to turn on/off this feature (default is on).

3. In dogfood, if a background started FGS with while-in-use permission
(any of location/camera/microphone) run into this restriction, the FGS
will not been granted these permission. we show a toast message to
alert user and ask them to write a bugreport using instruction at
go/r-bg-fgs-restriction. So we can have a statistic how many apps will
be impacted by this feature.
These is a flag Settings.Global.FOREGROUND_SERVICE_STARTS_LOGGING_ENABLED
to turn on/off the toast message (default is on, in dogfood)

Bug: 136219221
Test: atest android.app.cts.ActivityManagerProcessStateTest
atest android.app.cts.ActivityManagerApi29Test.java
atest android.app.cts.ActivityManagerFgsBgStartTest

Change-Id: Ibc8aaa6839a69136f9311bfacdbab9705b31b6a7