feat: Update API for contact avatar (#4719)

Added the ability to update the contact's avatar via API and Dashboard.

- Contact create and update APIs can now accept avatar attachment parameters [form data].
- Contact create and update endpoints can now accept the avatar_url parameter.[json]
- API endpoint to remove a contact avatar.
- Updated Contact create/edit UI components with avatar support

Fixes: #3428

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

@@ -148,6 +148,12 @@
         }
       }
     },
+    "DELETE_AVATAR": {
+      "API": {
+        "SUCCESS_MESSAGE": "Contact avatar deleted successfully",
+        "ERROR_MESSAGE": "Could not delete the contact avatar. Please try again later."
+      }
+    },
     "SUCCESS_MESSAGE": "Contact saved successfully",
     "ERROR_MESSAGE": "There was an error, please try again"
   },