"Deprecate" using an expression in model refs to interfaces

SocketBindingGroupResourceDefinition and OutboundSocketBindingResourceDefinition both have attributes that represent model refs to interface resources, but which also allow expressions.

Model references should not allow expressions. These were "grandfathered in" when the large scale expression support roll out happened for AS 7.2 / EAP 6.1.

There's no metadata facility to record that expression support is deprecated, but the add handler for these should log a WARN if they encounter an expression. Hopefully in EAP 8 we can then remove expression support.

We use INFO messages for other management API deprecation messages, but these I believe deserve a WARN. The issue here isn't just that we may change something in the future (seen as not justifying a WARN) but also that the capability/requirement bookkeeping for the attribute cannot be properly done if an expression is used, meaning the model integrity behavior meant to be in place cannot be used.

We should look for other cases like this too, although those changes should be separate JIRAs.