PLT-3077 Add group messaging (#5489)

* 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)

model/authorization.go

@@ -30,6 +30,7 @@ var PERMISSION_MANAGE_ROLES *Permission
 var PERMISSION_MANAGE_TEAM_ROLES *Permission
 var PERMISSION_MANAGE_CHANNEL_ROLES *Permission
 var PERMISSION_CREATE_DIRECT_CHANNEL *Permission
+var PERMISSION_CREATE_GROUP_CHANNEL *Permission
 var PERMISSION_MANAGE_PUBLIC_CHANNEL_PROPERTIES *Permission
 var PERMISSION_MANAGE_PRIVATE_CHANNEL_PROPERTIES *Permission
 var PERMISSION_LIST_TEAM_CHANNELS *Permission
@@ -149,6 +150,11 @@ func InitalizePermissions() {
 		"authentication.permissions.create_direct_channel.name",
 		"authentication.permissions.create_direct_channel.description",
 	}
+	PERMISSION_CREATE_GROUP_CHANNEL = &Permission{
+		"create_group_channel",
+		"authentication.permissions.create_group_channel.name",
+		"authentication.permissions.create_group_channel.description",
+	}
 	PERMISSION_MANAGE_PUBLIC_CHANNEL_PROPERTIES = &Permission{
 		"manage__publicchannel_properties",
 		"authentication.permissions.manage_public_channel_properties.name",
@@ -350,6 +356,7 @@ func InitalizeRoles() {
 		"authentication.roles.global_user.description",
 		[]string{
 			PERMISSION_CREATE_DIRECT_CHANNEL.Id,
+			PERMISSION_CREATE_GROUP_CHANNEL.Id,
 			PERMISSION_PERMANENT_DELETE_USER.Id,
 			PERMISSION_MANAGE_OAUTH.Id,
 		},