Function provider_takes_env 

pub fn provider_takes_env(unit: &str, provider: &str) -> bool

v0.18 decision 0021 / v0.19 decision 0025: which first-party provider classes take the Worker env as a constructor argument, keyed by (unit, provider class). SecretsProvider accepts an optional env with a globalThis probe fallback; WorkersKv requires env on use — KV namespaces exist only on the Worker env, never on globalThis.