Merge changes from topic "nabkah01/invalid_access"

* changes:
  test(tftf): prevent root region access from Realm world
  test(cactus): prevent root region access from swd
  test(tftf): prevent secure region access from Realm world
  test(tftf): prevent secure region access from nwd
  feat(ff-a): create function helper to setup FF-A mailbox