Allow configuration of an Elytron SSLContext in the IIOP subsystem

Currently the IIOP subsystem defines an attribute that references a JSSE security domain to obtain the key and trust managers used by the SSLSocketFactory to build an SSLContext instance.

With Elytron we now have a new capability that exposes SSLContext instances and we should be able to use that in the IIOP subsystem. A new attribute must be added to allow for the specification of the Elytron SSLContext that should be used. The SSLSocketFactory will still support the old JSSE-based configuration but will be able to make use of Elytron's centralized SSL configuration to obtain an SSLContext.