Variation on ConfigSSLEngineProvider that will periodically reload the keys and certificates
from disk, to facilitate rolling updates of certificates.
This class is still ApiMayChange because it can likely be further harmonized with
the standard ConfigSSLEngineProvider. Also the location and default values of the
configuration may change in future versions of Akka.
This provider does not perform hostname verification, but instead allows checking
that the remote certificate has a subject name that matches the subject name of
the configured certificate.