Support for Spigot Library loader

[mart-r]

Spigot added a Library loader functionality lately.
https://www.spigotmc.org/threads/spigot-bungeecord-1-17.510208/#post-4184317

What this means is that it should no longer be required that bStats be shaded within the plugin and relocated as Spigot should be able to handle the version control itself.
According to the post, in some circumstances this would even allow different plugins to use a different version of the same library according to the post.
However, I'm not entirely sure in which circumstances that refers to.

[Andret2344]

I did the PR to apply this change: #106