Upgrade to latest node-fetch

- Introduce injection tokens for retriving the implementation of
  node-fetch via await import() calls

- Add webpack file for compiling node-fetch to electron-renderer single
  file format

Signed-off-by: Sebastian Malton <sebastian@malton.name>

.gitignore

@@ -17,3 +17,4 @@ types/extension-renderer-api.d.ts
 extensions/*/dist
 docs/extensions/api
 site/
+build/webpack/