Make `#uri-slashes-hierarchical-identifier` a `spec::Requirement` in spec rdfa

[damooo]

Currently #uri-slashes-hierarchical-identifier is not an object on any statement with predicate spec:requirement in spec rdfa.

As it seems also n requirement to be enforced, though shared between server and client, if it is linked as other requirements, we can uniformly query it. requirement subject can be both client and server.

If at all it makes sense.

[csarven]

It does make sense and thanks for raising this.

Although the first two statements are not or need not be stated as a new requirement (already covered by RFC 3986):

The slash (/) character in the URI path indicates hierarchical relationship segments, and enables relative referencing [RFC3986]. The semantics of the slash character is shared by servers and clients.

The following statement can be:

Paths ending with a slash denote a container resource.

Worth noting that the section https://solidproject.org/ED/protocol#uri-slash-semantics is normative and so the statements (requirements) within the section should be testable. While the context of the statement is already clear, it be can be explicit with the subject of the requirement and the requirement level (for starters).

It that makes sense, I can paraphrase and update.

[damooo]

Indeed _/\_.

We just has programming language level constants for requirements. So that we can attach them to violation errors. They are generated from rdfa query. And thus the uri semantics requirement got missed in them.