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]>

licenserc.toml

@@ -0,0 +1,27 @@
+additionalHeaders = ["scripts/cz-header-style.toml"]
+
+headerPath = "scripts/license-header.txt"
+
+includes = [
+    "Makefile",
+    "*.Makefile",
+    "*.swift",
+    "*.h",
+    "*.cpp",
+    "*.c",
+    "*.sh",
+]
+
+excludes = [
+    "Sources/ContainerizationArchive/CArchive/include",
+]
+
+[git]
+attrs = 'enable'
+ignore = 'enable'
+
+[properties]
+copyrightOwner = "Apple Inc. and the Containerization project authors"
+
+[mapping.SWIFT_STYLE]
+extensions = ["swift"]