feat(voice): Improved voice call creation flow [EE] (#12268)

This PR improves the voice call creation flow by simplifying
configuration and automating setup with Twilio APIs.

references: #11602 , #11481 

## Key changes

- Removed the requirement for twiml_app_sid – provisioning is now
automated through APIs.
- Auto-configured webhook URLs for:
  - Voice number callbacks
  - Status callbacks
  -  twiML callbacks
- Disabled business hours, help center, and related options until voice
inbox is fully supported.
- Added a configuration tab in the voice inbox to display the required
Twilio URLs (to make verification easier in Twilio console).


## Test Cases
- Provisioning
- Create a new voice inbox → verify that Twilio app provisioning happens
automatically.
  - Verify twiML callback 
- Webhook configuration
- Check that both voice number callback and status callback URLs are
auto-populated in Twilio.
- Disabled features
- Confirm that business hours and help center options are
hidden/disabled for voice inbox.
- Configuration tab
- Open the voice inbox configuration tab → verify that the displayed
Twilio URLs match what’s set in Twilio.

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

@@ -330,13 +330,14 @@
             "LABEL": "API Key Secret",
             "PLACEHOLDER": "Enter your Twilio API Key Secret",
             "REQUIRED": "API Key Secret is required"
-          },
-          "TWIML_APP_SID": {
-            "LABEL": "TwiML App SID",
-            "PLACEHOLDER": "Enter your Twilio TwiML App SID (starts with AP)",
-            "REQUIRED": "TwiML App SID is required"
           }
         },
+        "CONFIGURATION": {
+          "TWILIO_VOICE_URL_TITLE": "Twilio Voice URL",
+          "TWILIO_VOICE_URL_SUBTITLE": "Configure this URL as the Voice URL on your Twilio phone number and TwiML App.",
+          "TWILIO_STATUS_URL_TITLE": "Twilio Status Callback URL",
+          "TWILIO_STATUS_URL_SUBTITLE": "Configure this URL as the Status Callback URL on your Twilio phone number."
+        },
         "SUBMIT_BUTTON": "Create Voice Channel",
         "API": {
           "ERROR_MESSAGE": "We were not able to create the voice channel"