Revert "[vm] Implement `Finalizer`"

This reverts commit 7dca34c23535287593595a3f570a714465556210.

Reason for revert: b/226085355 dart_vm_test crashing. Unclear what
the cause is. Reverting so we can triage the issue.

TEST=This is a revert.

Original change's description:
> [vm] Implement `Finalizer`
>
> This CL implements the `Finalizer` in the GC.
>
> (This CL does not yet implement `NativeFinalizer`.)
>
> The GC is specially aware of two types of objects for the purposes of
> running finalizers.
>
> 1) `FinalizerEntry`
> 2) `Finalizer` (`FinalizerBase`, `_FinalizerImpl`)
>
> A `FinalizerEntry` contains the `value`, the optional `detach` key, and
> the `token`, and a reference to the `finalizer`.
> An entry only holds on weakly to the value, detach key, and finalizer.
> (Similar to how `WeakReference` only holds on weakly to target).
>
> A `Finalizer` contains all entries, a list of entries of which the value
> is collected, and a reference to the isolate.
>
> When a the value of an entry is GCed, the enry is added over to the
> collected list.
> If any entry is moved to the collected list, a message is sent that
> invokes the finalizer to call the callback on all entries in that list.
>
> When a finalizer is detached by the user, the entry token is set to the
> entry itself and is removed from the all entries set.
> This ensures that if the entry was already moved to the collected list,
> the finalizer is not executed.
>
> To speed up detaching, we use a weak map from detach keys to list of
> entries. This ensures entries can be GCed.
>
> Both the scavenger and marker tasks process finalizer entries in
> parallel.
> Parallel tasks use an atomic exchange on the head of the collected
> entries list, ensuring no entries get lost.
> The mutator thread is guaranteed to be stopped when processing entries.
> This ensures that we do not need barriers for moving entries into the
> finalizers collected list.
> Dart reads and replaces the collected entries list also with an atomic
> exchange, ensuring the GC doesn't run in between a load/store.
>
> When a finalizer gets posted a message to process finalized objects, it
> is being kept alive by the message.
> An alternative design would be to pre-allocate a `WeakReference` in the
> finalizer pointing to the finalizer, and send that itself.
> This would be at the cost of an extra object.
>
> Send and exit is not supported in this CL, support will be added in a
> follow up CL. Trying to send will throw.
>
> Bug: https://github.com/dart-lang/sdk/issues/47777
>
> TEST=runtime/tests/vm/dart/finalizer/*
> TEST=runtime/tests/vm/dart_2/isolates/fast_object_copy_test.dart
> TEST=runtime/vm/object_test.cc
>
> Change-Id: I03e6b4a46212316254bf46ba3f2df333abaa686c
> Cq-Include-Trybots: luci.dart.try:vm-kernel-reload-rollback-linux-debug-x64-try,vm-kernel-reload-linux-debug-x64-try,vm-ffi-android-debug-arm64c-try,dart-sdk-mac-arm64-try,vm-kernel-mac-release-arm64-try,pkg-mac-release-arm64-try,vm-kernel-precomp-nnbd-mac-release-arm64-try,vm-kernel-win-debug-x64c-try,vm-kernel-win-debug-x64-try,vm-kernel-precomp-win-debug-x64c-try,vm-kernel-nnbd-win-release-ia32-try,vm-ffi-android-debug-arm-try,vm-precomp-ffi-qemu-linux-release-arm-try,vm-kernel-mac-debug-x64-try,vm-kernel-nnbd-mac-debug-x64-try,vm-kernel-nnbd-linux-debug-ia32-try,benchmark-linux-try,flutter-analyze-try,flutter-frontend-try,pkg-linux-debug-try,vm-kernel-asan-linux-release-x64-try,vm-kernel-gcc-linux-try,vm-kernel-optcounter-threshold-linux-release-x64-try,vm-kernel-precomp-linux-debug-simarm_x64-try,vm-kernel-precomp-obfuscate-linux-release-x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-debug-x64c-try
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/229544
> Reviewed-by: Lasse Nielsen <lrn@google.com>
> Reviewed-by: Slava Egorov <vegorov@google.com>
> Reviewed-by: Martin Kustermann <kustermann@google.com>
> Reviewed-by: Ryan Macnak <rmacnak@google.com>
> Commit-Queue: Daco Harkes <dacoharkes@google.com>

TBR=lrn@google.com,vegorov@google.com,kustermann@google.com,rmacnak@google.com,dacoharkes@google.com

Change-Id: I991f6e49896d18a8d70210cf315d858b462d66c9
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: https://github.com/dart-lang/sdk/issues/47777
Cq-Include-Trybots: luci.dart.try:vm-kernel-reload-rollback-linux-debug-x64-try,vm-kernel-reload-linux-debug-x64-try,vm-ffi-android-debug-arm64c-try,dart-sdk-mac-arm64-try,vm-kernel-mac-release-arm64-try,pkg-mac-release-arm64-try,vm-kernel-precomp-nnbd-mac-release-arm64-try,vm-kernel-win-debug-x64c-try,vm-kernel-win-debug-x64-try,vm-kernel-precomp-win-debug-x64c-try,vm-kernel-nnbd-win-release-ia32-try,vm-ffi-android-debug-arm-try,vm-precomp-ffi-qemu-linux-release-arm-try,vm-kernel-mac-debug-x64-try,vm-kernel-nnbd-mac-debug-x64-try,vm-kernel-nnbd-linux-debug-ia32-try,benchmark-linux-try,flutter-analyze-try,flutter-frontend-try,pkg-linux-debug-try,vm-kernel-asan-linux-release-x64-try,vm-kernel-gcc-linux-try,vm-kernel-optcounter-threshold-linux-release-x64-try,vm-kernel-precomp-linux-debug-simarm_x64-try,vm-kernel-precomp-obfuscate-linux-release-x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-debug-x64c-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/238080
Reviewed-by: Slava Egorov <vegorov@google.com>
Reviewed-by: Daco Harkes <dacoharkes@google.com>
Commit-Queue: Daco Harkes <dacoharkes@google.com>