chore: Add "Coming Soon" overlay to voice channel selector (#11835)

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Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>

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

@@ -49,5 +49,8 @@
     "HOURS": "Hours",
     "DAYS": "Days",
     "PLACEHOLDER": "Enter duration"
+  },
+  "CHANNEL_SELECTOR": {
+    "COMING_SOON": "Coming Soon!"
   }
 }