Add preinstall setup to build

Already had this in the release build step, not sure why it is not in
the main build step.  But we started getting errors building native
modules in ci, and this might be why.

Author: code-asher

.github/workflows/build.yaml

@@ -198,9 +198,14 @@ jobs:
       - name: Build vscode
         if: steps.cache-vscode.outputs.cache-hit != 'true'
         run: |
-          pushd lib/vscode
+          cd lib/vscode/build
           npm ci
-          popd
+          cd ..
+          source ./build/azure-pipelines/linux/setup-env.sh
+          # Run preinstall script before root dependencies are installed
+          # so that v8 headers are patched correctly for native modules.
+          node build/npm/preinstall.ts
+          cd ../..
           npm run build:vscode
       # Push up an artifact containing the linux-x64 release.
       - run: KEEP_MODULES=1 npm run release