chore: Standardize subpackages on npm instead of yarn (#371)

Summary:

Preparing for further CI changes by standardizing all packages on npm instead of yarn.
- Remove outdated yarn.lock files
- In datafile-manager, generate package-lock.json and remove yarn.lock
- In datafile-manager, set Typescript version to exactly 3.3.3333

Test plan:

Unit tests. Manually verified the output of the build in datafile-manager. It's exactly the same as it was before these changes.

Author: mjc1283