[Feature] Email collect message hooks (#331)

- Add email collect hook on creating conversation
- Merge contact if it already exist

app/javascript/widget/helpers/constants.js

@@ -9,4 +9,6 @@ export const MESSAGE_STATUS = {
 export const MESSAGE_TYPE = {
   INCOMING: 0,
   OUTGOING: 1,
+  ACTIVITY: 2,
+  TEMPLATE: 3,
 };