Pull HAL reads out of RecordThread resample

Previously, the resample was indirectly calling HAL read
from within the BufferProvider's getNextBuffer.  Now the HAL
read is done ahead of time into a circular buffer,
and the getNextBuffer just reads out of that memory.

This change will permit some future planned features.

Also removed the mono to mono resampling optimization,
as that optimization will no longer be valid in the future.

Change-Id: I59f5016a2df91078d697c37a7dec2d9d9f44542e