* Add check to catch syanpse master process starting when workers are configured

* add test to verify that starting master process with worker config raises error

* newsfragment

* specify config.worker.worker_app in check

* update test

* report specific config option that triggered the error

Co-authored-by: reivilibre <oliverw@matrix.org>

* clarify error message

Co-authored-by: reivilibre <oliverw@matrix.org>

Co-authored-by: reivilibre <oliverw@matrix.org>