Add composite action for setting up Rust environment and create test workflow

.github/actions/setup-rust/action.yml

@@ -0,0 +1,53 @@
+name: 'Setup Rust environment'
+description: 'Composite action to checkout the repo, restore cargo caches and set up the Rust toolchain. Use this from job steps to keep setup DRY across jobs.'
+inputs:
+  toolchain:
+    description: 'Rust toolchain to install'
+    required: false
+    default: 'stable'
+  override:
+    description: 'Whether to override the default toolchain'
+    required: false
+    default: 'true'
+  components:
+    description: 'Comma-separated list of additional rust components to install'
+    required: false
+    default: 'clippy, rustfmt'
+runs:
+  using: 'composite'
+  steps:
+    - name: Checkout repository
+      uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
+
+    - name: Cache cargo registry
+      uses: actions/cache@v3
+      with:
+        path: ~/.cargo/registry
+        key: ${{ runner.os }}-cargo-registry-${{ hashFiles('**/Cargo.lock') }}
+        restore-keys: |
+          ${{ runner.os }}-cargo-registry-${{ hashFiles('**/Cargo.lock') }}
+
+    - name: Cache cargo index
+      uses: actions/cache@v3
+      with:
+        path: ~/.cargo/index
+        key: ${{ runner.os }}-cargo-index-${{ hashFiles('**/Cargo.lock') }}
+        restore-keys: |
+          ${{ runner.os }}-cargo-index-${{ hashFiles('**/Cargo.lock') }}
+
+    - name: Cache cargo build (target)
+      uses: actions/cache@v3
+      with:
+        path: target
+        key: ${{ runner.os }}-cargo-build-${{ hashFiles('**/Cargo.lock') }}
+        restore-keys: |
+          ${{ runner.os }}-cargo-build-${{ hashFiles('**/Cargo.lock') }}
+
+    - name: Set up rust toolchain
+      uses: dtolnay/rust-toolchain@stable
+      with:
+        toolchain: ${{ inputs.toolchain }}
+        override: ${{ inputs.override }}
+        components: ${{ inputs.components }}