Proposal: rename feature_json to attributes

[bcodell]

This may be pedantic, but are you open to renaming references to features as attributes? Feature feels very much like borrowing from ML terminology, and while this framework can be used to power model training/serving pipelines, it also serves other use cases where the term feature is more foreign. I think adopting a term like attribute would make the framework a bit more intuitive and accessible to data/analytics engineers. Open to other terminology suggestions as well. Would love to hear the motivation for why the term feature was picked as well, as I'm sure other options were considered, and every option has tradeoffs.