Fix channel switcher routing for DMs with remote users (#25887)

webapp/channels/src/utils/path.ts

@@ -14,6 +14,7 @@ export const TEAM_NAME_PATH_PATTERN = '[a-z0-9\\-_]+';
 // - Group Channel Name (40 length UID)
 // - DM Name (userID__userID)
 // - Username prefixed by a @
+// - Username prefixed by a @, with colon and remote name e.g. @username:companyname
 // - User ID
 // - Email
-export const IDENTIFIER_PATH_PATTERN = '[@a-zA-Z\\-_0-9][@a-zA-Z\\-_0-9.]*';
+export const IDENTIFIER_PATH_PATTERN = '[@a-zA-Z\\-_0-9][@a-zA-Z\\-_0-9.:]*';