[top-level-await] Sync implementation with spec text

The module evaluation machinery has undergone non-trivial refactoring
since implementation. Sync up the comments and code for maintenance.

Notably,

- Actually use the kEvaluatingAsync status (previously conflated under
  kEvaluated)
- [[IsAsyncEvaluating]] -> [[IsAsyncEvaluation]]
- GatherAsyncParentCompletions -> GatherAvailableAncestors
- async -> has_toplevel_await
- kAsyncModule -> kModuleWithTopLevelAwait

Bug: 347060515
Change-Id: Ia2c35d5b42ee9f58db841cdfcaef9d17b018c9c6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/5636701
Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Cr-Commit-Position: refs/heads/main@{#94591}

test/staging/top-level-await/grandparent-tla_FIXTURE.js

@@ -0,0 +1,4 @@
+// Copyright (C) 2024 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+import "parent-tla_FIXTURE.js";

test/staging/top-level-await/parent-tla_FIXTURE.js

@@ -0,0 +1,4 @@
+// Copyright (C) 2024 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+import "tla_FIXTURE.js"

test/staging/top-level-await/tla-hang-entry.js

@@ -0,0 +1,13 @@
+// Copyright (C) 2024 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: module graphs with TLA shouldn't hang
+flags: [module, async]
+features: [top-level-await]
+---*/
+
+import "parent-tla_FIXTURE.js";
+await import("grandparent-tla_FIXTURE.js");
+
+$DONE();

test/staging/top-level-await/tla_FIXTURE.js

@@ -0,0 +1,4 @@
+// Copyright (C) 2024 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+await 0;