chore: VS Code settings

[Jinxit]

Description

Decided to split this from CI changes to make it an easier thing to get merged. There are now two main changes:

1. RA uses a separate target directory, meaning RA builds no longer cause rebuilds in nix, and vice versa.
2. The settings file has been renamed to settings.default.json, meaning developers can copy that file as a starting point but have their own settings that won't be committed to the repo.

Important points for reviewers

If you don't make a copy of settings.default.json as settings.json after this is merged, you won't have the right settings in VS Code.

Checklist

• Are there important points that reviewers should know?
  • See above.
• Make sure that you described what this change does.
• If there are follow-ups, have you created issues for them?
• Have you tested this solution?
• Were there any alternative implementations considered?
• Did you document new (or modified) APIs?

[jmg-duarte]

LGTM. I wonder if there's a way to tell git "dont actually delete settings.json locally, just remove from cache"