feat(core): Reland support for async ops in realms

[andreubotella]

Currently realms are supported on deno_core, but there was no support for async ops anywhere other than the main realm. The main issue is that the js_recv_cb callback, which resolves promises corresponding to async ops, was only set for the main realm, so async ops in other realms would never resolve. Furthermore, promise ID's are specific to each realm, which meant that async ops from other realms would result in a wrong promise from the main realm being resolved.

This change takes the ContextState struct added in #17050, and adds to it a js_recv_cb callback for each realm. Combined with the fact that that same PR also added a list of known realms to JsRuntimeState, and that #17174 made OpCtx instances realm-specific and had them include an index into that list of known realms, this makes it possible to know the current realm in the queue_async_op and queue_fast_async_op methods, and therefore to send the results of promises for each realm to that realm, and prevent the ID's from getting mixed up.

Additionally, since promise ID's are no longer unique to the isolate, having a single set of unrefed ops doesn't work. This change therefore also moves unrefed_ops from JsRuntimeState to ContextState, and adds the lengths of the unrefed op sets for all known realms to get the total number of unrefed ops to compare in the event loop.

This PR is a reland of #14734 after it was reverted in #16366, except that ContextState and JsRuntimeState::known_realms were previously relanded in #17050. Another significant difference with the original PR is passing around an index into JsRuntimeState::known_realms instead of a v8::Global<v8::Context> to identify the realm, because async op queuing in fast calls cannot call into V8, and therefore cannot have access to V8 globals. This also simplified the implementation of resolve_async_ops.

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cc @lmalheiro, since the this reland includes a test they provided for the original PR.

[andreubotella]

main:

test bench_op_async   ... bench:     576,647 ns/iter (+/- 35,813)

this PR:

test bench_op_async   ... bench:     613,201 ns/iter (+/- 32,075)

There seems to be a clear decrease in performance in this benchmark. Now, bench_op_async only goes through the ready and non-deferred match arm of queue_async_op, so this points finely enough at a perf issue in the change, but it also leaves the rest of branches unchecked. Are there some other specific async op benchmarks that I can use for the other codepaths?

[andreubotella]

I got rid of a v8::Global clone (which was there before this PR) in the ready, non-deferred arm of queue_async_op and got the benchmark down. It's still noticeably higher than in the main branch though.

test bench_op_async   ... bench:     590,218 ns/iter (+/- 25,768)

[andreubotella]

PTAL @bartlomieju @littledivy

[bartlomieju]

@littledivy this looks good to me now - I think having a separate code path for non-default realm is a good idea.

[bartlomieju]

Oooops, looks like #17301 causes the tests to fail, could you update them @andreubotella?

[littledivy]

LGTM!

[bartlomieju]

LGTM too, thanks Andreu