audio: Add playback rate parameters to IStreamOut

Playback rate parameters allow changing the playback speed
of audio streams optionally preserving the pitch (this is
often referred to as "timestretch"). HALs can apply these
parameters when decoding of streams is done in hardware.

Bug: 133526565
Test: atest VtsHalAudioV6_0TargetTest
Change-Id: Ie78cd924bd034b57bf5b6a74affd62641ffc0aba