Add CLI/Python command to update an API without needing to specify the entire API configuration

[deliahu]

Description

For example, the user could specify the API name and the predictor.config, which will then be applied to the API.

A more general solution would be that the user could specify whatever fields they want, and the operator would perform a "merge" operation (with overwrites) to construct the desired API config. One question with this approach is how to perform the merge (there are different approaches for doing this, e.g. kubernetes provides different types of patch updates).

Motivation

Simplify CI/CD workflows