Split Ambient Display settings.
1. Reverting the changes for Display->Ambient Display; this setting
will control incoming notification pulse.
2. Added 2 separate entries in gestures settings to control pick up
and double tap gestures-triggered pulsing for Ambient Display.
3. Added automated tests to verify the preference initializes to the
correct default value, and also verify that toggling the preference
updates the corresponding settings correctly.
Test: make SettingsTests
Bug:
30595437
Change-Id: I125bf75fc4ccfea126a00ffae4207fcb789f487a