MM-24595 Migrate API handler getChannelMember(s) to be compatible with local mode (#14533)

Co-authored-by: Ibrahim Serdar Acikgoz <serdaracikgoz86@gmail.com>
Co-authored-by: Miguel de la Cruz <miguel@mcrx.me>
Co-authored-by: mattermod <mattermod@users.noreply.github.com>

app/authorization.go

@@ -44,7 +44,9 @@ func (a *App) SessionHasPermissionToChannel(session model.Session, channelId str
 	if channelId == "" {
 		return false
 	}
-
+	if session.IsUnrestricted() {
+		return true
+	}
 	ids, err := a.Srv().Store.Channel().GetAllChannelMembersForUser(session.UserId, true, true)
 
 	var channelRoles []string