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
- API to fetch info of a single inbox
- Document passing custom_attributes in the API
- Ability to filter contacts with contact identifier in search API
* Add Conversation factory with dependent factories
* Include FactoryBot methods in rspec config
* Add unit tests for public methods of Conversation model
* Move Current model into a separate file in lib folder
* Disable Metrics/BlockLength rule for db/migrate and spec folders
* Get rid of global $dispatcher variable
* Create Message#unread_since scope
* Refactor callback methods in Conversation model
* Create Conversations::EventDataPresenter
* Add translation keys for activity messages
* Add pry-rails gem
* Refactor Conversation#notify_status_change
* Add mock_redis for test env
