This commit updates type declarations for Worker to accept specifiers
as either strings or URL, bringing it in line with TypeScript
declarations and browser behavior.
This commit rewrites implementation of "JsRuntime::mod_evaluate".
Event loop is no longer polled automatically and users must manually
drive event loop forward after calling "mod_evaluate".
Co-authored-by: Nayeem Rahman <nayeemrmn99@gmail.com>
Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>
