Allow .zed/tasks.json local configs (#8536)

![image](https://github.com/zed-industries/zed/assets/2690773/e1511777-b4ca-469e-8636-1e513b615368)

Follow-up of
https://github.com/zed-industries/zed/issues/7108#issuecomment-1960746397

Makes more clear where each task came from, auto (re)load
.zed/config.json changes, properly filtering out other worktree tasks.

Release Notes:

- Added local task configurations
ac30ded80eKirill Bulatov committed on 2/28/2024, 11:18:13 PM· committed by GitHubparent7f954cb
12 files changedLine totals unavailable