SEC15 — get_security_names

Summary: e have a SecurityMechandNameList get_security_names(in Object objref);
on SecurityLevel2::Current.

Since we have this capability, we should have a similar way of getting the
mechanisms and options.

Unfortunately, Security::MechandOptions struct only contains options
supported and does not have options required. The only place it is used is
for Vault::get_supported_mechs();

We should probably have another structure to handle the mechs on the
object reference. We will call this the mechanism data as not to confuse
it with MechandOptions struct.

:Current.