feat: Voice Channel (#11602)

Enables agents to initiate outbound calls and receive incoming calls
directly from the Chatwoot dashboard, with Twilio as the initial
provider.

Fixes:  #11481 

> This is an integration branch to ensure features works well and might
be often broken on down merges, we will be extracting the
functionalities via smaller PRs into develop

- [x] https://github.com/chatwoot/chatwoot/pull/11775
- [x] https://github.com/chatwoot/chatwoot/pull/12218
- [x] https://github.com/chatwoot/chatwoot/pull/12243
- [x] https://github.com/chatwoot/chatwoot/pull/12268
- [x] https://github.com/chatwoot/chatwoot/pull/12361
- [x]  https://github.com/chatwoot/chatwoot/pull/12782
- [x] #13064
- [ ] Ability for agents to join the inbound calls ( included in this PR
)

---------

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>
Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>
Co-authored-by: iamsivin <iamsivin@gmail.com>
Co-authored-by: Pranav <pranav@chatwoot.com>

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

@@ -275,6 +275,16 @@
     "SIDEBAR": {
       "CONTACT": "Contact",
       "COPILOT": "Copilot"
+    },
+    "VOICE_WIDGET": {
+      "INCOMING_CALL": "Incoming call",
+      "OUTGOING_CALL": "Outgoing call",
+      "CALL_IN_PROGRESS": "Call in progress",
+      "NOT_ANSWERED_YET": "Not answered yet",
+      "HANDLED_IN_ANOTHER_TAB": "Being handled in another tab",
+      "REJECT_CALL": "Reject",
+      "JOIN_CALL": "Join call",
+      "END_CALL": "End call"
     }
   },
   "EMAIL_TRANSCRIPT": {