Make connections to the Erlang Port Mapper Daemon (epmd) optional
in Jinterface when providing a custom transport factory, as is
possible for Erlang nodes with the -no_epmd -proto_dist options.
The existing Jinterface classes and interfaces have been designed
originally for transport protocols using a socket port number and
didn't support other protocols working without epmd.
To provide backward compatibility and avoid code duplication,
create a new OtpGenericTransportFactory abstract class which does
not expect a socket port number but use the peer and local nodes
instead as generic identifiers. This expands the Jinterface
compatibility to other protocols, for instance Unix Domain Sockets.
Adapt AbstractConnection, AbstractNode, OtpNode and OtpSelf to
accept factory subclasses of the new OtpGenericTransportFactory and
make them compatible with a wider set of alternative distribution
protocols. With such transport factory subclasses, epmd is not used
at all whereas the behavior remains unchanged for regular factories.
Add documentation and test case for OtpGenericTransportFactory