runtime: run syscall/js finalizers on wasm without a manual GC (#5545)

* runtime: run syscall/js finalizers on wasm without a manual GC

* runtime: address review feedback on finalizer idle GC

* runtime: clear a finished task's args pointer so its arguments are collectable

* runtime: skip the finalizer scan with a per-block registration bit

* runtime: guard the finalizer registration bitmap with gcLock

* testdata: cover finalizer invariants on every scheduler

* main_test: limit the finalizer scheduler variants to linux and darwin

* testdata: wait for the finalizer queue to drain before asserting

* testdata: make the finalizer counters atomic and wait for a known drain count

* runtime: add finalizer bookkeeping asserts under runtime_asserts

* runtime: address finalizer GC review feedback

* testdata: strengthen blocked stack finalizer test

* runtime: fix finalizer cleanup edge cases

* runtime: decouple wasm export scheduling from finalizers

* runtime: avoid redundant wakeups for re-entrant wasm exports

* runtime: simplify finalizer comments

testdata/finalizerlarge.go

@@ -0,0 +1,29 @@
+package main
+
+import "runtime"
+
+type largeFinalizerObject struct {
+	data [128]byte
+}
+
+var largeFinalizerRan bool
+
+//go:noinline
+func registerLargeFinalizer() {
+	p := new(largeFinalizerObject)
+	runtime.SetFinalizer(p, func(*largeFinalizerObject) {
+		largeFinalizerRan = true
+	})
+}
+
+func main() {
+	registerLargeFinalizer()
+	for i := 0; i < 100 && !largeFinalizerRan; i++ {
+		runtime.GC()
+		runtime.Gosched()
+	}
+	if !largeFinalizerRan {
+		panic("large object finalizer did not run")
+	}
+	println("ok")
+}