Run PHP CS strict on 4 extensions

CLDR, TranslationNotifications, TwnMainPage and ULS. Only on check,
possibly to later be made voting.

References:
* https://gerrit.wikimedia.org/r/#/c/88626
* https://gerrit.wikimedia.org/r/#/c/88635

Depends on Change-Id I95ba7ca87c6ce93ef97a0b7c54c88832b0a32ccf.

Change-Id: Iec223a59a72432e95bde256247f40d27c6b90f70