Summary:
Renames each package to match `@pixie/xyz`, and remove the `private: true` designation in the non-root packages. This involved quite a bit of fiddling with Yarn's `nohoist` and some incorrectly specified dependencies/imports.
The root was renamed as well to prepare it for moving its code into `src/ui/packages/`. That future change will untangle shared configuration from that specific to `@pixie/ui`, simplifying the dependency graph as well as module resolutions.

Test Plan: Run a fresh `yarn install --force` in `src/ui`. Build and smoke test. No-op change for now.

Reviewers: michelle, vihang, #engineering

Reviewed By: vihang, #engineering

JIRA Issues: PC-736

Differential Revision: https://phab.corp.pixielabs.ai/D7406

GitOrigin-RevId: 8f6d8b2df64c97e6a2db3e91e41ee5152e5005f8