New VA108xx Rust workspace structure + dependency updates

- The workspace is now a monorepo without submodules. The HAL, PAC and BSP
  are integrated directly
- Update all dependencies: embedded-hal v1 and RTIC v2

.github/workflows/ci.yml

@@ -0,0 +1,49 @@
+name: ci
+on: [push, pull_request]
+
+jobs:
+  check:
+    name: Check build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: "thumbv6m-none-eabi"
+      - run: cargo check --release
+      - run: cargo check --examples --release
+
+  test:
+    name: Run Tests
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+      - name: Install nextest
+        uses: taiki-e/install-action@nextest
+      - run: cargo nextest run --all-features
+      - run: cargo test --doc
+
+  fmt:
+    name: Check formatting
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+      - run: cargo fmt --all -- --check
+
+  docs:
+    name: Check Documentation Build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@nightly
+      - run: cargo +nightly doc --all-features --config 'build.rustdocflags=["--cfg", "docs_rs"]'
+
+  clippy:
+    name: Clippy
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+      - run: cargo clippy -- -D warnings