Include waveform when sending voice messages (#1650)

- New `AudioLevelCalculator` that outputs dB0v rescaled to the [0;1] range.
- `VoiceRecorder` now stores the audio levels sampled while recording, then resamples them to 100 samples to use as waveform preview.
- Waveform data is carried all the way as a `List<Float>` and converted to `List<Int>` in the [0;1024] range as per matrix spec only before sending it.

libraries/voicerecorder/test/src/main/kotlin/io/element/android/libraries/voicerecorder/test/FakeVoiceRecorder.kt

@@ -70,7 +70,11 @@ class FakeVoiceRecorder(
         _state.emit(
             when (curRecording) {
                 null -> VoiceRecorderState.Idle
-                else -> VoiceRecorderState.Finished(curRecording!!, "audio/ogg")
+                else -> VoiceRecorderState.Finished(
+                    file = curRecording!!,
+                    mimeType = "audio/ogg",
+                    waveform = listOf(0f, 1f, 2f, 3f, 4f, 5f, 6f, 7f, 8f, 9f, 8f, 7f, 6f, 5f, 4f, 3f, 2f, 1f, 0f),
+                )
             }
         )
     }