Vendor apple/containerization with a VM-extensions forwarding patch

Switch the containerization dependency from the github URL to a vendored copy
(third_party/containerization, upstream commit 6b7b42ca) referenced by path, so
we can carry a small local patch that upstream lacks: LinuxContainer.Configuration
gains a `vmExtensions` field forwarded into VMConfiguration.extensions. Upstream
already supports VMConfiguration.extensions + the VZInstanceExtension hook, but
LinuxContainer — our only entry point — never forwarded them, so there was no way
to attach a device (e.g. a memory balloon) to a container's VM.

Tests/, docs/, examples/, images/ and the corresponding test targets are trimmed
for footprint (we never build the dependency's tests). See PATCHES.md for the full
diff vs. upstream and the re-vendoring procedure. Also adds the ContainerizationExtras
product to NucleicCore (AddressAllocator, named in the configureVZ signature).

Co-Authored-By: Claude Opus 4.8 <[email protected]>

scripts/install-hawkeye.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/env bash 
+# Copyright © 2025-2026 Apple Inc. and the Containerization project authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#   https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+if command -v .local/bin/hawkeye >/dev/null 2>&1; then
+    echo "hawkeye already installed"
+else
+    echo "Installing hawkeye"
+    export VERSION=v6.5.1
+    curl --proto '=https' --tlsv1.2 -LsSf https://github.com/korandoru/hawkeye/releases/download/${VERSION}/hawkeye-installer.sh | CARGO_HOME=.local sh -s -- --no-modify-path
+fi