server(filesystem): rebuild everything imaginable

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>

server/transfer/archive.go

@@ -35,8 +35,8 @@ type Archive struct {
 func NewArchive(t *Transfer, size uint64) *Archive {
 	return &Archive{
 		archive: &filesystem.Archive{
-			BasePath: t.Server.Filesystem().Path(),
-			Progress: progress.NewProgress(size),
+			Filesystem: t.Server.Filesystem(),
+			Progress:   progress.NewProgress(size),
 		},
 	}
 }