ci: Add CI workflow

.github/actions/libextism/action.yaml

@@ -0,0 +1,32 @@
+on: [workflow_call]
+
+name: libextism
+description: Installs Extism runtime from git
+
+runs:
+  using: composite
+  steps:
+    - uses: actions/checkout@v3
+    - uses: actions-rs/toolchain@v1
+      with:
+        toolchain: stable
+    - uses: actions/setup-python@v4
+      with:
+        python-version: '3.10' 
+    - name: Install Extism
+      shell: bash
+      run: |
+          pip install poetry
+          pip install git+https://github.com/extism/cli
+          extism install git
+    - name: Upload libextism.so
+      uses: actions/upload-artifact@v2
+      with:
+        name: libextism-so-artifact
+        path: /usr/local/lib/libextism.so
+    - name: Upload libextism.h
+      uses: actions/upload-artifact@v2
+      with:
+        name: libextism-h-artifact
+        path: /usr/local/include/extism.h
+

.github/workflows/ci.yaml

@@ -0,0 +1,44 @@
+name: Zig CI
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  zig:
+    name: Zig CI
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest]
+        zig_version: ["master"] # eventually use multiple versions once stable
+        rust:
+          - stable
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v3
+      - name: Download libextism.so
+        uses: actions/download-artifact@v2
+        with:
+          name: libextism-so-artifact
+      - name: Download libextism.h
+        uses: actions/download-artifact@v2
+        with:
+          name: libextism-h-artifact
+      - name: Move the files because download can't sudo
+        run: |
+          ls -lah ./
+          sudo mv libextism.so /usr/local/lib/
+          sudo mv extism.h /usr/local/include/
+      - name: Setup Zig env
+        uses: goto-bus-stop/setup-zig@v2
+        with: 
+          version: ${{ matrix.zig_version }}
+
+      - name: Test Zig Host SDK
+        run: |
+          zig version
+          cd zig
+          LD_LIBRARY_PATH=/usr/local/lib zig build test