Send a broadcast when turning grayscale off

When users turn grayscale off in Settings, Settings will send an intent
to receivers who have requested the CONTROL_DISPLAY_COLOR_TRANSFORMS
permission. We also specify FLAG_RECIEVER_INCLUDE_BACKGROUND to make
sure that the intent could be sent to manifest receivers.

Bug: 118387886
Test: robotests
Change-Id: Ib0c959e72dd4068014951347df35409790c77ab5