Description of the new feature/enhancement
For example, there's currently a manifest for Ditto in the repo: https://github.com/microsoft/winget-pkgs/blob/master/manifests/Ditto/Ditto/3.22.88.0.yaml. The directory is Ditto\Ditto, but the package ID is ditto.ditto. These should match so the directory to look up is deterministic from the ID, and validation should check that at PR time. By the same token, I could create a PR for Ditto with the directory ditto\ditto and that'd be allowed, even though those two directories wouldn't be allowed on Windows, differing only by case.
Proposed technical implementation details (optional)
A PR validation step should be added that ensures the manifest's directory and ID match in casing, and that there are no other manifest folders that differ only by capitalization.