add package step to gh actions

.github/workflows/main.yml

@@ -28,4 +28,34 @@ jobs:
             ${{ runner.os }}-
       - run: npm run lint
         env:
-          DISPLAY: ":99.0"
+          DISPLAY: ":99.0"
+  package:
+    runs-on: ubuntu-latest
+    needs: lint
+    name: Package
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-node@v2
+        with:
+          node-version: "14"
+      - run: npm install
+      - name: Cache node modules
+        uses: actions/cache@v2
+        env:
+          cache-name: cache-node-modules
+        with:
+          # npm cache files are stored in `~/.npm` on Linux/macOS
+          path: ~/.npm
+          key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ hashFiles('**/package-lock.json') }}
+          restore-keys: |
+            ${{ runner.os }}-build-${{ env.cache-name }}-
+            ${{ runner.os }}-build-
+            ${{ runner.os }}-
+      - run: npm install -g vsce
+      - run: vsce package
+      - run: echo "VSIX_PATH=$(find . -maxdepth 1 -type f -iname "*.vsix" | head -1)" >> $GITHUB_ENV
+      - run: echo "VSIX_NAME=$(basename $(find . -maxdepth 1 -type f -iname "*.vsix" | head -1))" >> $GITHUB_ENV
+      - uses: actions/upload-artifact@v2
+        with:
+          path: ${{ env.VSIX_PATH }}
+          name: ${{ env.VSIX_NAME }}