Rename the method to setBlockable. Also rename isBlockableSystem in the
same way.
Bug: 151311073
Test: atest NotificationChannelTest
Change-Id: I0504f8043dc864fe6677f2e65783068ffa3437ba
The notification package was getting too big.
Test: make -j64 RunSettingsRoboTests
Fixes: 145224451
Change-Id: I25ba82f42f7a137d8adcce72dcf8089d0e018bdc