feat(windows-drivers): vendor wdk 0.5.1 + add ApiSubset::Iddcx (M1 spike)

Vendor the published, self-contained windows-drivers-rs 0.5.1 crates
(wdk-build, wdk-sys) under vendor/ and add a first-class ApiSubset::Iddcx that
bindgens iddcx/1.10/IddCx.h in an extra pass reusing bindgen::Builder::wdk_default
(allowlist_file (?i).*iddcx.* — emits only IddCx items; WDF/DXGI types resolve to
the shared base/wdf bindings, type-identity by construction). Mirrors the existing
gpio/hid/spb subsets exactly: wdk-build gets the enum variant + iddcx_headers()
(UMDF-only), wdk-sys gets generate_iddcx + the iddcx feature + pub mod iddcx.
[patch.crates-io] redirects all wdk-sys/wdk-build (incl. wdk 0.4.1 transitive) to
the patched copies. wdk-probe enables the iddcx feature.

MAKE-OR-BREAK: does IddCx.h bindgen in wdk-sys config without a header conflict
(issue #515) + does the generated module compile (type-identity)? CI answers it.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packaging/windows/drivers/vendor/wdk-sys/src/wdf.rs

@@ -0,0 +1,35 @@
+// Copyright (c) Microsoft Corporation
+// License: MIT OR Apache-2.0
+
+//! Direct FFI bindings to WDF APIs from the Windows Driver Kit (WDK)
+//!
+//! This module contains all bindings to functions, constants, methods,
+//! constructors and destructors in `wdf.h`. Types are not included in this
+//! module, but are available in the top-level `wdk_sys` module.
+
+pub use bindings::*;
+
+#[allow(missing_docs)]
+#[allow(clippy::unreadable_literal)]
+mod bindings {
+    #[allow(
+        clippy::wildcard_imports,
+        reason = "the underlying c code relies on all type definitions being in scope, which \
+                  results in the bindgen generated code relying on the generated types being in \
+                  scope as well"
+    )]
+    use crate::types::*;
+
+    include!(concat!(env!("OUT_DIR"), "/wdf.rs"));
+}
+
+// This is a workaround to expose the generated function count to the
+// `call_unsafe_wdf_function_binding` proc-macro, so that the macro-generated
+// code can determine the slice size at runtime. When we are able to
+// conditionally compile based off a cfg range for WDF version, this module
+// can be removed and the runtime check can be replaced with a conditional
+// compilation: https://github.com/microsoft/windows-drivers-rs/issues/276
+#[doc(hidden)]
+pub mod __private {
+    include!(concat!(env!("OUT_DIR"), "/wdf_function_count.rs"));
+}