Undertow subsystem lacks capability references between its filter and filter-ref

Undertow defines a filter-ref resource, which must have a matching filter resource with the same name, however there are no capability references that enforce this relationship. A server configuration containing a filter-ref with no matching filter will cause the server to fail to start with a missing service MSC exception.

I suggest we generalize the capabililty defined by the ModClusterDefinition, which is completely unreferenced currently.