Expose SoundTriggerManager and SoundTrigger APIs

These APIs require a system permissions, hence SystemAPI.

As SoundTrigger is now partially SystemApi and partially internal API a
lot of @hide tags are needed to keep hiding the still internal classes,
fields and methods. As SoundTrigger is heavily used via reflection no
structural change to this class can be made.

The MANAGE_SOUND_TRIGGER permission should be visible to the apps as
the apps need to know which permission to request in their manifest.
If it wouldn't be exposed it would just be a magic string.

Test: built
Change-Id: Ic93d67639e2605c26c961acdd827c14cb0a68f47
Bug: 73829108, 71981721