Add support for WebRTC Auto Gain and Noise Suppression (#250)

## WebRTC Auto Gain & Noise Suppression
 
This PR adds support for WebRTC Auto Gain and Noise Suppression as previously implemented in the Wyoming Satellite project.
 
### What's New
 
Two new entities have been created a number slider for gain and another one for noise suppression. The processing happens inside of the `webrtc.py` file and is implemented in the `__main__.py` file's `process_audio` function. The slider for gain has a limit of 0-31 and noise suppression has a limit of 0-4.
 
The Auto Gain and Noise Suppression persist through restarts and are saved as preferences. The values are dynamically chnged without needing a restart.
 
CLI flags called `--mic-auto-gain` and `--mic-noise-suppression` have also been added.
 
>  When both values are 0, WebRTC processing is bypassed entirely with no performance overhead.

Closes #25 
 
### Testing
 
When saving the audio recorded by LVA there is a noticeable increase. The following two files have been recorded with similar audio being played through them with these results (Gain-31 and NS-4):
 
| Metric | With AGC+NS | Without |
|---|---|---|
| Max amplitude | 0.329 | 0.054 |
| RMS amplitude | 0.008905 | 0.002862 |
| Volume adjustment needed | 3.034x | 13.479x |
| Rough frequency | 916 Hz | 705 Hz |

README.md

@@ -51,7 +51,7 @@ For all other users we have different installation methods available (Docker, sy
 💡 **Note:** There is a [environment variable](docs/install_application.md#environment-variables-reference) for each parameter if you use docker or systemd based setup.
 
 ``` sh
-usage: __main__.py [-h] [--name NAME] [--audio-input-device AUDIO_INPUT_DEVICE] [--list-input-devices] [--audio-input-block-size AUDIO_INPUT_BLOCK_SIZE] [--audio-output-device AUDIO_OUTPUT_DEVICE] [--list-output-devices] [--wake-word-dir WAKE_WORD_DIR]
+usage: __main__.py [-h] [--name NAME] [--audio-input-device AUDIO_INPUT_DEVICE] [--list-input-devices] [--audio-input-block-size AUDIO_INPUT_BLOCK_SIZE] [--audio-output-device AUDIO_OUTPUT_DEVICE] [--list-output-devices] [--wake-word-dir WAKE_WORD_DIR]  [--mic-auto-gain] [--mic-noise-suppression]
                    [--wake-model WAKE_MODEL] [--stop-model STOP_MODEL] [--download-dir DOWNLOAD_DIR] [--refractory-seconds REFRACTORY_SECONDS] [--wakeup-sound WAKEUP_SOUND] [--timer-finished-sound TIMER_FINISHED_SOUND] [--processing-sound PROCESSING_SOUND]
                    [--mute-sound MUTE_SOUND] [--unmute-sound UNMUTE_SOUND] [--preferences-file PREFERENCES_FILE] [--host HOST] [--network-interface NETWORK_INTERFACE] [--port PORT] [--enable-thinking-sound] [--debug]
 ```
@@ -62,6 +62,8 @@ usage: __main__.py [-h] [--name NAME] [--audio-input-device AUDIO_INPUT_DEVICE]
 | `--audio-input-device` | Soundcard name for input device | Autodetected |
 | `--audio-input-block-size` | Audio input block size in samples | 1024 |
 | `--audio-output-device` | mpv name for output device | Autodetected |
+| `--mic-auto-gain` | Add WebRTC Gain to Mic | 0 |
+| `--mic-noise-suppression` | Add WebRTC Noise Suppression to Mic | 0 |
 | `--wake-word-dir` | Directory with wake word models (.tflite) and configs (.json) | `wakewords/` |
 | `--wake-model` | ID of active wake word model | `okay_nabu` |
 | `--stop-model` | ID of stop model | `stop` |
@@ -81,6 +83,8 @@ usage: __main__.py [-h] [--name NAME] [--audio-input-device AUDIO_INPUT_DEVICE]
 | `--debug` | Print DEBUG messages to console | False |
 | `--output-only` | Enable output only mode | False |
 
+💡 **Note:** There is a detailed explanation on the gain and noise suppression flags in the [audio options](docs/audio_options.md) file.
+
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