add offloaded audio visualizer

Add library for visualizer effect used when
audio decompression is offloaded to QCOM audio DSP.
The implementation reads PCM back from the proxy port
in the audio DSP.
The audio HAL dynamically loads the effect library if present
and indicates offloaded output activity.
The PCM capture is only active when an offloaded output
is active and at least one effect is enabled on this output.

Bug: 8174410.

Change-Id: Ic78de932f9116e246494f9171c1cc7c3e35a0ea1