Extended Information-forwarding support

[Xernium]

This PR brings Waterfall on a forwarding-feature-level with Velocity for better security. Implemented:

• Velocity modern forwarding support, courtesy of @astei and the Velocity contributors, this forwarding mode uses a 1.13 and newer feature for a more standardised and less volatile forwarding solution.
• Bungeeguard forwarding support (natively), courtesy of @lucko this forwarding type is an extension to the standard/legacy Bungeecord forwarding protocol which adds another field/token for authentication.

This PR is soon to be accompanied by a PR to update the PaperMC/PaperDocs with information on all of this