Velocity Plugin Support

[phase]

I've talked to @astei about hosting Velocity plugins on Ore and he is in support of it.
They will be using their own velocity-plugin.json for now, and he said he'll consider the Forge TOML format once it has been finalized. Either way, adding support for Velocity to Ore will not be a difficult once #644 and #646 are merged in.

Since Velocity offers (or will offer) first class Sponge support, I want to add first class Velocity support to Ore. I want to wait a little bit until the platform becomes stable before we start throwing Velocity plugins on Ore that won't work later down the line (the Plugin API for Velocity just got merged, so it'll be a little bit).

This ticket will serve as a tracking issue for Velocity Plugin support in Ore. Currently all that "support" requires is a metadata parser and a platform tag. More will be discussed about accepted platforms on Ore in the next SPAM.

Related to #527

[XakepSDK]

What is velocity? Link please

[felixoi]

@XakepSDK https://www.velocitypowered.com/

[Katrix]

We have decided that for now, Ore will focus on the platforms we touch directly. As such I am closing this issue. People reading this are welcome to submit a PR to add the appropriate plugin loader to Ore, but even if they do, we will not enable it in our instance of Ore.