Modules: reject asynchronous work during module initialization

Modules: reject asynchronous work during module initialization

Global code is intended for synchronous initialization, but Fetch and
timers could start request-bound work before clone publication.  QuickJS
Fetch dereferenced the unpublished engine, and module-level timers could
escape initialization.

Reject Fetch, setTimeout(), and setImmediate() before argument conversion
or resource allocation in both engines.  This does not prohibit ordinary
promise jobs or synchronous module initialization.