Migrate audio pipeline to float from 16-bit integer (#2873)

Co-authored-by: Cameron Gutman <aicommander@gmail.com>

src/platform/common.h

@@ -525,7 +525,7 @@ namespace platf {
   class mic_t {
   public:
     virtual capture_e
-    sample(std::vector<std::int16_t> &frame_buffer) = 0;
+    sample(std::vector<float> &frame_buffer) = 0;
 
     virtual ~mic_t() = default;
   };