Add a command to reload permissions.yml

[Byteflux]

The permissions.yml file is an underrated feature that is extremely helpful for server networks that offer global ranks and permissions. It offers a way for server owners to conveniently define permission nodes that are specific to a server, without worrying about those permissions leaking to other servers.

Currently, the permissions.yml file is only reloadable using the /reload command, which as we all know is very unsafe and prone to memory leaks. There exists plugins that do what permissions.yml does with the added benefit of being able to reload, and they work great, but this is something that can be easily accomplished in Paper with negligible maintenance overhead.

I'm leaving an issue here as a reminder for me to implement this when I get a chance. If any one else feels like tackling this, you're more than welcome to do so :)