Ability to send HCI commands from Rust

* Autogenerate packet code in Rust from PDL (packet file copied from rootcanal)
* Implement parsing of packets that have a type header
* Expose Python APIs for sending HCI commands
* Expose Python APIs for instantiating a local controller

rust/src/wrapper/link.rs

@@ -0,0 +1,38 @@
+// Copyright 2023 Google LLC
+//
+// 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
+//
+//     http://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.
+
+//! Link components
+use pyo3::{intern, types::PyModule, PyObject, PyResult, Python, ToPyObject};
+
+/// Link bus for controllers to communicate with each other
+#[derive(Clone)]
+pub struct Link(pub(crate) PyObject);
+
+impl Link {
+    /// Creates a [Link] object that transports messages locally
+    pub fn new_local_link() -> PyResult<Self> {
+        Python::with_gil(|py| {
+            PyModule::import(py, intern!(py, "bumble.link"))?
+                .getattr(intern!(py, "LocalLink"))?
+                .call0()
+                .map(|any| Self(any.into()))
+        })
+    }
+}
+
+impl ToPyObject for Link {
+    fn to_object(&self, _py: Python<'_>) -> PyObject {
+        self.0.clone()
+    }
+}