Channel banner permissions (#30917)

* Fixed save state panel for channel banner

* Defined default background color

* Updated test

* WIP

* wip

* removed unused param

* Updated tests

* CI

* Fixed mmctl test

* Fixed TestDoAdvancedPermissionsMigration test

* Test update

* lint fix

* lint fix

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/cmd/mmctl/commands/permissions_test.go

@@ -246,6 +246,8 @@ func (s *MmctlUnitTestSuite) TestResetPermissionsCmd() {
 			"edit_bookmark_private_channel",
 			"delete_bookmark_private_channel",
 			"order_bookmark_private_channel",
+			"manage_public_channel_banner",
+			"manage_private_channel_banner",
 		}
 		expectedPatch := &model.RolePatch{
 			Permissions: &expectedPermissions,