feat: Ability to send voice message to channel (#4064)

Created the possibility to send audio as an attachment via the dashboard.
The channels that can send audio are the same channels that can send any type of attachment.
Used RecordRTC (https://github.com/muaz-khan/RecordRTC) to capture the audio and Wavesurfer (https://github.com/katspaugh/wavesurfer.js) to display the audio waves.
RecordRTC can be used to record videos if necessary.

Fixes #1973

app/javascript/dashboard/i18n/locale/en/conversation.json

@@ -74,8 +74,14 @@
       "TIP_FORMAT_ICON": "Show rich text editor",
       "TIP_EMOJI_ICON": "Show emoji selector",
       "TIP_ATTACH_ICON": "Attach files",
+      "TIP_AUDIORECORDER_ICON": "Record audio",
+      "TIP_AUDIORECORDER_PERMISSION": "Allow access to audio",
+      "TIP_AUDIORECORDER_ERROR": "Could not open the audio",
       "ENTER_TO_SEND": "Enter to send",
       "DRAG_DROP": "Drag and drop here to attach",
+      "START_AUDIO_RECORDING": "Start audio recording",
+      "STOP_AUDIO_RECORDING": "Stop audio recording",
+      "": "",
       "EMAIL_HEAD": {
         "ADD_BCC": "Add bcc",
         "CC": {