Don't shade packetevents

[vytskalt]

I think it would be great if packetevents wasn't shaded in the library and it was up to the user to do so. In my case I already depend on ProtocolLib in my plugin so I don't need packetevents to be included.

[derklaro]

I will try to take a look into publishing a version with and one without packetevents shaded soon-ish.

[portlek]

@derklaro you can split the packetevents implementation into another module so people can still use that with adding new module's dependency.

[vytskalt]

Or it could use compileOnly on packetevents and then check at runtime if packetevents is in the classpath. This way it would also be possible to use the standalone packetevents plugin