MM-22212 & MM-22208: Read from the higher-scoped scheme if the permission is non-moderated. (#13813)

* MM-22212: Read non-moderated permissions from higher-scoped scheme.

* MM-2212: Corrects test count in comment.

* MM-22212: Adds godoc comment.

* MM-2212: Switches to the channel roles check in a few more places.

* MM-22212: Refactors and fixes.

* MM-22212: Reverts change, no longer required.

* MM-22212: Removes translation.

* MM-22212: Un-comments merged new permission.

* MM-22212: Un-comments merged new permission.

* MM-22212: Performance tweak.

* MM-22212: Fixes some fmting.

* MM-22212: Add unit test for newly-added store methods.

* MM-22212: Renames app method.

* MM-22212: Re-uses existing function to find string in slice.

* MM-22212: Keeps 'higher-scoped' terminology for consistency.

* MM-22212: Refactors based on PR feedback.

* MM-22212: Fix for some bad merging.

* MM-22212: Renamed some things.

* MM-22212: Use an 'else' instead of a 'continue' for readability.

* MM-22212: Caches (*SqlRoleStore).ChannelRolesUnderTeamRole.

* MM-22212: Adds mock to new cache store.

* MM-22212: Adds missing open tracing app layer methods.

* MM-22212: Adds migration to add moderated permissions to channel_admin if present on channel_user.

* MM-22212: Migrates team schemes. Removes unused AppError.

* MM-22212: Fix for for if.

* MM-22212: Fixes iterator.

* MM-22212: Updates open tracing generated methods.

* MM-22212: Fix mocks.

* MM-22212: Change migration key name.

* MM-22212: Switched to data structure from other branch.

* MM-22212: Fixes tests after adding 'use_channel_mentions' to the channel_admin role.

* MM-22212: Adds tracking of channel moderation.

* Revert "MM-22212: Adds tracking of channel moderation."

This reverts commit 23689efa22c112e4ba37f6a212535dd7ebfb63db.

* MM-22212: Switch some functions to methods and vice versa.

* MM-22212: Fix for refactor bug not notifiying websocket about changed role.

* MM-22212: Adds test for public/private 'manage_members' handling.

* MM-22122 Fix manage channel members edge case for public and private channels (#14049)

* MM-22212: Adds moderated permission to team_admin.

* MM-22212: Updates migration.

* MM-22212: Revert unnecessary update to default roles.

* Add channel scheme updated event when channel scheme is deleted or created (#14057)

* MM-22212: Adds newline.

* MM-22212: Migration fix.

* MM-22212: Fix for migration.

* MM-22212: Test fix.

Co-authored-by: Farhan Munshi <3207297+fm2munsh@users.noreply.github.com>

utils/utils.go

@@ -19,6 +19,7 @@ func StringInSlice(a string, slice []string) bool {
 	return false
 }
 
+// RemoveStringFromSlice removes the first occurrence of a from slice.
 func RemoveStringFromSlice(a string, slice []string) []string {
 	for i, str := range slice {
 		if str == a {
@@ -28,6 +29,19 @@ func RemoveStringFromSlice(a string, slice []string) []string {
 	return slice
 }
 
+// RemoveStringsFromSlice removes all occurrences of strings from slice.
+func RemoveStringsFromSlice(slice []string, strings ...string) []string {
+	newSlice := []string{}
+
+	for _, item := range slice {
+		if !StringInSlice(item, strings) {
+			newSlice = append(newSlice, item)
+		}
+	}
+
+	return newSlice
+}
+
 func StringArrayIntersection(arr1, arr2 []string) []string {
 	arrMap := map[string]bool{}
 	result := []string{}