Extend security context propagation test coverage:

• add servlet-to-ejb credential propagation scenarios (BASIC, FORM, BEARER)
• add tests for manual credentials retrieving (use in *-to-servlet scenarios)
• credential-less propagation
• clustered scenarios for authorization forwarding
• sequence of more authentication/authorization forwarding mode calls
• exception propagation to previous server
• negative scenario for credentials not being accessible on forwarded server after authorization forwarding
• identity switching on one remote connection for
  • authentication and authorization switching
  • authorization and different authorization switching