Resolve the ConnectionState a context carries: the context's own state when
it implements ConnectionScoped and resolved one, otherwise null.
Centralised here (mirroring connectionTokenOf) so the server core has one
place to decide per-session/per-request state vs. the single bound
activeConnection fallback. A null result means "this
context carries no scoped state" — the dispatcher then uses
activeConnection.
Resolve the ConnectionState a context carries: the context's own state when it implements ConnectionScoped and resolved one, otherwise null. Centralised here (mirroring connectionTokenOf) so the server core has one place to decide per-session/per-request state vs. the single bound activeConnection fallback. A null result means "this context carries no scoped state" — the dispatcher then uses activeConnection.