This wonderfully large commit replaces basically everything under the
`server/filesystem` package, re-implementing essentially everything.
This is related to
https://github.com/pterodactyl/wings/security/advisories/GHSA-494h-9924-xww9
If any vulnerabilities related to symlinks persist after this commit, I
will be very upset.
Signed-off-by: Matthew Penner <me@matthewp.io>
