[Flight] Clarify Semantics for Awaiting Cached Data (facebook#33438)

Technically the async call graph spans basically all the way back to the
start of the app potentially, but we don't want to include everything.
Similarly we don't want to include everything from previous components
in every child component. So we need some heuristics for filtering out
data.

We roughly want to be able to inspect is what might contribute to a
Suspense loading sequence even if it didn't this time e.g. due to a race
condition.

One flaw with the previous approach was that awaiting a cached promise
in a sibling that happened to finish after another sibling would be
excluded. However, in a different race condition that might end up being
used so I wanted to include an empty "await" in that scenario to have
some association from that component.

However, for data that resolved fully before the request even started,
it's a little different. This can be things that are part of the start
up sequence of the app or externally cached data. We decided that this
should be excluded because it doesn't contribute to the loading sequence
in the expected scenario. I.e. if it's cached. Things that end up being
cache misses would still be included. If you want to test externally
cached data misses, then it's up to you or the framework to simulate
those. E.g. by dropping the cache. This also helps free up some noise
since static / cached data can be excluded in visualizations.

I also apply this principle to forwarding debug info. If you reuse a
cached RSC payload, then the Server Component render time and its awaits
gets clamped to the caller as if it has zero render/await time. The I/O
entry is still back dated but if it was fully resolved before we started
then it's completely excluded.

Author: sebmarkbage

packages/react-client/src/__tests__/ReactFlight-test.js

@@ -2826,46 +2826,46 @@ describe('ReactFlight', () => {
       expect(getDebugInfo(thirdPartyChildren[0])).toEqual(
         __DEV__
           ? [
-              {time: 14},
+              {time: 22}, // Clamped to the start
               {
                 name: 'ThirdPartyComponent',
                 env: 'third-party',
                 key: null,
                 stack: '    in Object.<anonymous> (at **)',
                 props: {},
               },
-              {time: 15},
+              {time: 22},
               {time: 23}, // This last one is when the promise resolved into the first party.
             ]
           : undefined,
       );
       expect(getDebugInfo(thirdPartyChildren[1])).toEqual(
         __DEV__
           ? [
-              {time: 16},
+              {time: 22}, // Clamped to the start
               {
                 name: 'ThirdPartyLazyComponent',
                 env: 'third-party',
                 key: null,
                 stack: '    in myLazy (at **)\n    in lazyInitializer (at **)',
                 props: {},
               },
-              {time: 17},
+              {time: 22},
             ]
           : undefined,
       );
       expect(getDebugInfo(thirdPartyChildren[2])).toEqual(
         __DEV__
           ? [
-              {time: 12},
+              {time: 22},
               {
                 name: 'ThirdPartyFragmentComponent',
                 env: 'third-party',
                 key: '3',
                 stack: '    in Object.<anonymous> (at **)',
                 props: {},
               },
-              {time: 13},
+              {time: 22},
             ]
           : undefined,
       );
@@ -2967,15 +2967,15 @@ describe('ReactFlight', () => {
       expect(getDebugInfo(thirdPartyFragment.props.children)).toEqual(
         __DEV__
           ? [
-              {time: 12},
+              {time: 19}, // Clamp to the start
               {
                 name: 'ThirdPartyAsyncIterableComponent',
                 env: 'third-party',
                 key: null,
                 stack: '    in Object.<anonymous> (at **)',
                 props: {},
               },
-              {time: 13},
+              {time: 19},
             ]
           : undefined,
       );