Extract project_core out of project (#8438)

That's done to unblock work for dynamic tasks (`task` crate has to
access the worktree yet it is a dependency of a `project`).
Release Notes:

- N/A
009384f948Piotr Osiewicz committed on 2/26/2024, 9:09:22 PM· committed by GitHubparent72009de
15 files changedLine totals unavailable