[Flight] Emit the time we awaited something inside a Server Component #33402
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This is different than the I/O start/end because it represents the time that an await was blocked where as other work can have been done between the start and when we awaited.
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Stacked on #33402. There's a bug in Chrome Performance tracking which uses the enclosing line/column instead of the callsite in stacks. For our fake eval:ed functions that represents functions on the server, we can position the enclosing function body at the position of the callsite to simulate getting the right line. Unfortunately, that doesn't give us exactly the right callsite when it's used for other purposes that uses the callsite like console logs and error reporting and stacks inside breakpoints. So I don't think we want to always do this. For ReactAsyncInfo/ReactIOInfo, the only thing we're going to use the fake task for is the Performance tracking, so it doesn't have any downsides until Chrome fixes the bug and we'd have to revert it. Therefore this PR uses that techniques only for those entries. We could do this for Server Components too but we're going to use those for other things too like console logs. I don't think it's worth duplicating the Task objects. That would also make it inconsistent with Client Components. For Client Components, we could in theory also generate fake evals but that would be way slower since there's so many of them and currently we rely on the native implementation for those. So doesn't seem worth fixing. But since we can at least fix it for RSC I/O/awaits we can do this hack.
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Stacked on #33400.
This is emitted with the start/end time and stack of the "await". Which may be different than the thing that started the I/O.
These awaits aren't quite as simple as just every await since you can start a sequence in parallel there can actually be multiple overlapping awaits and there can be CPU work interleaved with the await on the same component.
This has two "I/O" awaits but those are actually happening in parallel with
doWork().Since these also could have started before we started rendering this sequence (e.g. a component) we have to clamp it so that we don't consider awaits that start before the component.
What we're conceptually trying to convey is the time this component was blocked due to that I/O resource. Whether it's blocked from completing the last result or if it's blocked from issuing a waterfall request.