* PLT-7206: UI changes. Removed last user in channel loophole, refactored code to clean it up, added differentiated support for public and private channels, added unit tests. Still need to implement server-side checks
* PLT-7206: All helper methods in channel_utils.jsx now accept the same three boolean variables in the same order and use the same boolean logic to check their values.
* PLT-7206: Added unit tests for showManagementOptions(...)
* PLT-7206: Fixed test case descriptions
* Added unit tests for showCreateOption(...)
* PLT-7206: Added unit tests for canManageMembers(...)
* PLT-7206: Removed last person in channel loophole from server-side code
* PLT-7206: Reverted config.json
* PLT-7206: Fixed double negatives in unit test names
* PLT-7206: PR feedback - Removed confusing comment and unused variable
* channel delete option is hidden from the menu unless there is appropriate permissions as set in the policy page
* apply to public channel only and add restriction to API layer
* updated channel deletion
* 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)
* PLT-5080 (WebApp): Channel Admin permission level.
For channel management and channel deletion.
* Fix some incorrect showing/hiding of options.
* Remove incorrect client calls that was overwriting my channel members.
