PreProcessing: Data conversions for webrtc module and AEC check

Add conversions between float and int16_t for inputs and outputs
Add a check to execute ProcessReverseStream only for AEC effect

Bug:305866207
Test: atest VtsHalAECTargetTest
      atest VtsHalNSTargetTest
      atest VtsHalAGC1TargetTest
      atest VtsHalAGC2TargetTest

Change-Id: Ifb96bd03f170e3ce306ee2bfa9856c2caac9e413