Make not to ignore *.code-workspace

Make not to ignore *.code-workspace

**Reasons for making this change:**

Workspace file can allow you to have an individual VS Code setting file for each project, which is useful for monorepo-based development.

You can find an example on [lit/lit/lit-next.code-workspace](https://github.com/lit/lit/blob/08f60328abf83113fe82c9d8ee43dc71f10a9b77/lit-next.code-workspace).

**Links to documentation supporting these rule changes:**

https://code.visualstudio.com/docs/editor/multi-root-workspaces#_workspace-file