Proof-of-concept Rust wrapper

This contains Rust wrappers around enough of the Python API to implement Rust versions of the `battery_client` and `run_scanner` examples. The goal is to gather feedback on the approach, and of course to show that it is possible.

The module structure mirrors that of the Python. The Rust API is not optimally Rust-y, but given the constraints of everything having to delegate to Python, it's at least usable.

Notably, this does not yet solve the packaging problem: users must have an appropriate virtualenv, libpython, etc. [PyOxidizer](https://github.com/indygreg/PyOxidizer) may be a viable path there.

.github/workflows/python-build-test.yml

@@ -41,3 +41,20 @@ jobs:
       run: |
         inv build
         inv build.mkdocs
+  build-rust:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out from Git
+        uses: actions/checkout@v3
+      - name: Set up Python
+        uses: actions/setup-python@v4
+        with:
+          python-version: '3.10'
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          python -m pip install ".[build,test,development,documentation]"
+      - name: Install Rust toolchain
+        uses: actions-rust-lang/setup-rust-toolchain@v1
+      - name: Rust Tests
+        run: cd rust && cargo build --all-targets && cargo test