Relands #19463. This time the `ExtensionFileSourceCode` enum is
preserved, so this effectively just splits feature
`include_js_for_snapshotting` into `exclude_js_sources` and
`runtime_js_sources`, adds a `force_include_js_sources` option on
`extension!()`, and unifies `ext::Init_ops_and_esm()` and
`ext::init_ops()` into `ext::init()`.
A few easy migrations of module code from the runtime to the module map.
The module map already has a few places where it needs a handle scope,
so we're not coupling it any further with the v8 runtime.
`init_runtime_module_map` is replaced with an option to reduce API
surface of JsRuntime.
`module_resolve_callback` now lives in the `ModuleMap` and we use a
annex data to avoid having to go through the `Rc<RefCell<...>>` stored
in the `JsRuntime`'s isolate.
This is a quick first refactoring to split the tests out of runtime and
move runtime-related code to a top-level runtime module.
There will be a followup to refactor imports a bit, but this is the
major change that will most likely conflict with other work and I want
to merge it early.
