Add yarn.lock and update .gitignore

- Remove yarn.lock from .gitignore (it should be committed)
- Add yarn.lock (353KB) for consistent dependency resolution
- Fixes GitHub Actions error: 'Dependencies lock file is not found'

Author: danieltruong

.gitignore

@@ -28,7 +28,6 @@ npm-debug.log
 testem.log
 /typings
 yarn-error.log
-yarn.lock
 debug.log
 output.txt