feat(boundaries): ignore nested workspaces (vercel#9840)

### Description

Nested workspaces break a lot of our boundaries checks. This PR adds a
setting to glob walking to ignore nested workspaces, and uses it for
boundaries.

### Testing Instructions

Added a test to `turborepo-globwalk` for the underlying setting. And
added a nested package to `boundaries` fixture

Author: NicholasLYang