This change adds [LeftHook](https://lefthook.dev/) as a GitHub hook management tool alongside [MegaLinter](https://megalinter.io/) to lint all relevant files within the repository.
This change addresses some general housecleaning for CDN hosts:
* Removing all hosts that do not resolve
* Removing any rogue whitespaces in CDN `.txt` files
* Removing hirez CDN (as the only host could not be resolved)