OptionalcontributorThe feature's contributor; its dynamic half runs on the created scope (its static half is seeded
elsewhere). Optional: a scope can exist purely as a named region that OTHERS contribute into (the
script editor's, contributed by its toolbar and its editor commands) — the create/dispose/region
plumbing is the same either way.
OptionaldataThe single per-instance context bundle passed to dynamic. Memoize it — a new object re-runs it.
The child's tree key (or { key, name } when the registry name differs from the key).
The declarative form accepted by CommandScopeProvider in place of a pre-built scope: "create a
scopeNamechild of the container's ambient scope, run thecontributor'sdynamichalf on it for its lifetime, and provide it." DRYs the create-child + contribute + provide boilerplate. The scope tree mirrors the container tree because the child is created off useCommandScope.