refactor/local-manifest

[quinnwai]

In __init__.py, we are currently using the manifest as a shared variable between methods. This causes some confusing dev moments like...

• having trouble mocking out the manifest during [unit] testing
• keeping track of use cases of variables called by each method
• wanting to use a particular vrs_anvil function in isolation in Python

We should find a more scoped alternative to the manifest.

[quinnwai]

marked as won't do for now