Bundle VS Code node_modules to avoid yarn dependency

Many random bizarre issues otherwise.

Also includes misc improvements to docs and scripts.

ci/build/clean.sh

@@ -3,10 +3,22 @@ set -euo pipefail
 
 main() {
   cd "$(dirname "${0}")/../.."
+  source ./ci/lib.sh
 
-  git clean -Xffd
-  git submodule foreach --recursive git clean -xffd
-  git submodule foreach --recursive git reset --hard
+  rm -Rf \
+    out \
+    release \
+    release-static \
+    release-packages \
+    release-gcp \
+    dist \
+    .tsbuildinfo \
+    .cache/out.tsbuildinfo
+
+  pushd lib/vscode
+  git clean -xffd
+  git reset --hard
+  popd
 }
 
 main "$@"