[Fiber] Don't work on scheduled tasks while we're in an async commit …

…but flush it eagerly if we're sync (#31987)

This is a follow up to #31930 and a prerequisite for #31975.

With View Transitions, the commit phase becomes async which means that
other work can sneak in between. We need to be resilient to that.

This PR first refactors the flushMutationEffects and flushLayoutEffects
to use module scope variables to track its arguments so we can defer
them. It shares these with how we were already doing it for
flushPendingEffects.

We also track how far along the commit phase we are so we know what we
have left to flush.

Then callers of flushPassiveEffects become flushPendingEffects. That
helper synchronously flushes any remaining phases we've yet to commit.
That ensure that things are at least consistent if that happens.

Finally, when we are using a scheduled task, we don't do any work. This
ensures that we're not flushing any work too early if we could've
deferred it. This still ensures that we always do flush it before
starting any new work on any root so new roots observe the committed
state.

There are some unfortunate effects that could happen from allowing
things to flush eagerly. Such as if a flushSync sneaks in before
startViewTransition, it'll skip the animation. If it's during a
suspensey font it'll start the transition before the font has loaded
which might be better than breaking flushSync. It'll also potentially
flush passive effects inside the startViewTransition which should
typically be ok.

DiffTrain build for [defffdb](defffdb)

compiled/facebook-www/REVISION

@@ -1 +1 @@
-301a18a6afeaea9c6113d7e459025ba69f436b24
+defffdbba43f89b95d9f67a4fb0fa146c1211734

compiled/facebook-www/REVISION_TRANSFORMS

@@ -1 +1 @@
-301a18a6afeaea9c6113d7e459025ba69f436b24
+defffdbba43f89b95d9f67a4fb0fa146c1211734

compiled/facebook-www/React-dev.classic.js

@@ -1942,7 +1942,7 @@ __DEV__ &&
     exports.useTransition = function () {
       return resolveDispatcher().useTransition();
     };
-    exports.version = "19.1.0-www-classic-301a18a6-20250106";
+    exports.version = "19.1.0-www-classic-defffdbb-20250106";
     "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
       "function" ===
         typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&

compiled/facebook-www/React-dev.modern.js

@@ -1942,7 +1942,7 @@ __DEV__ &&
     exports.useTransition = function () {
       return resolveDispatcher().useTransition();
     };
-    exports.version = "19.1.0-www-modern-301a18a6-20250106";
+    exports.version = "19.1.0-www-modern-defffdbb-20250106";
     "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
       "function" ===
         typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&

compiled/facebook-www/React-prod.classic.js

@@ -630,4 +630,4 @@ exports.useSyncExternalStore = function (
 exports.useTransition = function () {
   return ReactSharedInternals.H.useTransition();
 };
-exports.version = "19.1.0-www-classic-301a18a6-20250106";
+exports.version = "19.1.0-www-classic-defffdbb-20250106";

compiled/facebook-www/React-prod.modern.js

@@ -630,4 +630,4 @@ exports.useSyncExternalStore = function (
 exports.useTransition = function () {
   return ReactSharedInternals.H.useTransition();
 };
-exports.version = "19.1.0-www-modern-301a18a6-20250106";
+exports.version = "19.1.0-www-modern-defffdbb-20250106";

compiled/facebook-www/React-profiling.classic.js

@@ -634,7 +634,7 @@ exports.useSyncExternalStore = function (
 exports.useTransition = function () {
   return ReactSharedInternals.H.useTransition();
 };
-exports.version = "19.1.0-www-classic-301a18a6-20250106";
+exports.version = "19.1.0-www-classic-defffdbb-20250106";
 "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
   "function" ===
     typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&

compiled/facebook-www/React-profiling.modern.js

@@ -634,7 +634,7 @@ exports.useSyncExternalStore = function (
 exports.useTransition = function () {
   return ReactSharedInternals.H.useTransition();
 };
-exports.version = "19.1.0-www-modern-301a18a6-20250106";
+exports.version = "19.1.0-www-modern-defffdbb-20250106";
 "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
   "function" ===
     typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&