Add ability to inherit resources

Motivation:

to be able to have stable resources which name and structure will be backward compatible even between major releases (e.g. something like /subsystem=web-abstract) and which could be inherited/implemented by resources which bring more configuration possibilities but may not be backward compatible between major releases (like e.g. /subsystem=undertow).

This would give users the possibility to write stable CLI/HTTP API/whatever automation if they use stable (parent) resources. There will still remain the option to use full configuration options offered by the implementing (children) resources but without backward compatibility guarantee.