`sh:order` should have its clarified `xsd:integer` usage encoded in SHACL-SHACL

[ajnelson-nist]

This is a follow-on to #479 . I was out of office, otherwise would have suggested this as part of #480 .

SHACL-SHACL should get a shape covering what is currently encoded as a comment in Turtle. If I'm understanding current documentation and test practice, a test should be added as well, and a dfn anchor should be added to the HTML providing sh:order.

[ajnelson-nist]

I'll tag this as Core because sh:order was part of SHACL 1.0, but if it should be part of UI instead, anybody should feel free to add that tag and/or replace Core.

[HolgerKnublauch]

@ajnelson-nist what do you see here as a work item for the Core spec? You mention a dfn anchor, but where would that go?

(If you have intentionally combined stuff for Core and SHACL-SHACL into a single ticket, it would be best to have a single PR, so you may just want to take ownership of the issue).