todo: fix tests after workspaces migration script is run

[iuioiua]

I've yet to investigate this properly. I am putting this here in case someone can get to it before me. To fix:

1. Run the migration script using deno run -A _tools/convert_to_workspace.ts.
2. Run deno task test.
3. Fix any test failures.
4. Submit a PR of the fixes, excluding the migration script changes.

[kt3k]

Files with test failures:

• crypto/crypto_test.ts chore(crypto): move test scripts to own files #4367
• fs/empty_dir_test.ts fix(fs): emptyDir() test after workspace conversion #4427
• fs/expand_glob_test.ts fix(fs): expandGlob() test after workspace conversion #4428
• http/file_server_test.ts chore(http): fix spawned tests after migration script #4368

[iuioiua]

This has been completed in the above PRs.