Proposal to reorganize

rules/core

and

engine

before we open up V2 to plugin authors in 1.28.x (the release where we’ll start to require writing V2 bindings for custom targets). Feedback appreciated! https://docs.google.com/document/d/16ClX8I1Wjr8fo6a6VVEAvPPTZISQGfD_HYaqAQ5q21M/edit#