Make mounts significantly more useful

[gp-Airee]

Hi. I saw #4520 was closed and nobody has directly brought this back up in the discussions - mounts have been very limited for a very long time. The application API has no power over it, the server install process has no power over it, the only way to interact with the mount selection on a server is over the admin page for the server. Custom mounts open up a lot of versatility within Pterodactyl, and I think any way to automate the management of mounts on servers would be huge.