Decide which classes MUST have `id`

[azaroth42]

3.0 says that all resources must have id, however we introduce in 4 a LOT of new classes, including selectors, cameras, lights, unitValues and so on. The most egregious cases are AudioContentSelector which only has type and no other properties, and the other bnodes like the metadata values which have label and value.

Suggestion is to keep the current 3.0 list in the appendix, plus:
Scene, Timeline and Service

Everything else MAY have an id

Thanks to @aisaac at 2025 Conference for pushing on this