libaudioprocessing: clamp application provided float audio

For security reason, float buffers provided by application must be
clamped to FLOAT_NOMINAL_RANGE_HEADROOM.
With the new all float pipeline, float are no longer clamped by their
conversion to fixed point.

This patch adds a float buffer provider that clamps float samples
as they are copied to audio pipeline.

Test: Play music, play video in chrome (opensles format float),
      play float pcm audio file specially crafter with >> 1 samples.
Bug: 68099072
Change-Id: I220b436d9982bc43a75715a030efd0e6a0c79fa3
Signed-off-by: Kevin Rocard <krocard@google.com>