Improvements in the list command and configuration loading

Unnecessary use of File was replaced by Path and Files
Improved the use of CompletableFutures when pinging a server
Improved performance when pinging servers using multiple threads via Parallel Streams. This feature was not specifically tested here, but it is what I use in my own plugins to ping multiple servers at the same time, reducing the waiting time to receive all the pings https://github.com/4drian3d/VServerInfo/blob/main/src/main/java/me/adrianed/vserverinfo/commands/ServerInfoCommand.java#L71

On a side note, the method ProxyServer#getAllServers() returns an immutable collection, so there is no need to do a Collection#stream#toList

fooooooooooooooo / VelocityDiscord