* Implement server changes for group messaging
* Majority of client-side implementation
* Some server updates
* Added new React multiselect component
* Fix style issues
* Add custom renderer for options
* Fix model test
* Update ENTER functionality for multiselect control
* Remove buttons from multiselect UI control
* Updating group messaging UI (#5524)
* Move filter controls up a component level
* Scroll with arrow keys
* Updating mobile layout for multiselect (#5534)
* Fix race condition when backspacing quickly
* Hidden or new GMs show up for regular messages
* Add overriding of number remaining text
* Add UI filtering for team if config setting set
* Add icon to channel switcher and class prop to status icon
* Minor updates per feedback
* Improving group messaging UI (#5563)
* UX changes per feedback
* Update email for group messages
* UI fixes for group messaging (#5587)
* Fix missing localization string
* Add maximum users message when adding members to GM
* Fix input clearing on Android
* Updating group messaging UI (#5603)
* Updating UI for group messaging (#5604)
* Fix push notifications where channel is set to all activity
* feedback review
* moved push notification logic to DoesStatusAllowPushNotification
* Have every option handled in ShouldSendPushNotification
* unit tests
* PLT-3193 Add channel notification preferences for push and email notifications
* unit tests, model validation and localization
* Feedback review
* Adding back allowFromCache check
* Setting push and email to use default settings
* Move props as constants
* address feedback
* Implement POST /channels/members/{user_id}/view endpoint for APIv4
* Implement PUT /channels/{channel_id}/members/{user_id}/roles endpoint for APIv4
* Implement DELETE /channels/{channel_id}/members/{user_id} endpoint for APIv4
* added get session and revoke session endpoints, unittests and drivers
* removed BasicUser2 and added teardown
* added badrequest unit test case for sessions
* added session loop to check if user id and session user id matches
* fixed indentation issues for user_test
* match indentation from spaces to tabs
* implement get channels endpoints and updated drivers and unittests
* removed channel deletion on tear down, removed manage permission on get channels endpoints, and updated utils to add constant channel length
* added constants for user, team and channel length, updated context to use the model functions
* make sure team name length should be less than the minimum length and revert underscore to team name validity
* changed post test condition from notfound to unauthorized
