feat: outbound voice call essentials (#12782)

- Enables outbound voice calls in voice channel . We are only caring
about wiring the logic to trigger outgoing calls to the call button
introduced in previous PRs. We will connect it to call component in
subsequent PRs

ref: #11602 

## Screens

<img width="2304" height="1202" alt="image"
src="https://github.com/user-attachments/assets/b91543a8-8d4e-4229-bd80-9727b42c7b0f"
/>

<img width="2304" height="1200" alt="image"
src="https://github.com/user-attachments/assets/1a1dad2a-8cb2-4aa2-9702-c062416556a7"
/>

---------

Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>
Co-authored-by: iamsivin <iamsivin@gmail.com>
Co-authored-by: Vishnu Narayanan <vishnu@chatwoot.com>

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

@@ -18,7 +18,8 @@
     "CREATED_AT_LABEL": "Created",
     "NEW_MESSAGE": "New message",
     "CALL": "Call",
-    "CALL_UNDER_DEVELOPMENT": "Calling is under development",
+    "CALL_INITIATED": "Calling the contact…",
+    "CALL_FAILED": "Unable to start the call. Please try again.",
     "VOICE_INBOX_PICKER": {
       "TITLE": "Choose a voice inbox"
     },