Is your feature request related to a problem? Please describe.
Feast feature repos are essentially declarative python code. When we make changes to the API used to declare Feast objects, we have to deprecate old fields, introduce new fields, and support both for multiple releases giving users a chance to upgrade their repos.

This pushes a lot of migration work on to users and is generally a non-scalable process.

Describe the solution you'd like

We should be able to automate trivial upgrades to the feature definitions (for things such as field renames or similar refactoring) automatically, in the same way as terraform.

There are tools like pybowler and fissix that allow for refactoring code.

We can integrate these into a feast upgrade command.