Fix Zen mode for different notification usage types

ZenModeHelper was only considering a subset of all notification usage
 types. The code was also iterating over the usage values, expecting
 them to be contiguous, which will break with the addition of new
 usage values.
The update consists in:
 - defining in AudioAttributes an array of expected usage types
 - defining the suppression behavior for each usage type
 - have ZenModeHelper query the behavior for each usage in
    order to apply the corresponding muting behavior.

Bug 29009099

Change-Id: If884dda6297f125c60c5775c757df4f782e22e53