1.12.19 - Add ability to forward status event behind Velocity proxy & 1.21.4 preparations
This adds a new feature (toggleable with accept-forwarded-bukkit-events) which allows working around the Velocity behaviour of not allowing the resource pack status packet to reach the Minecraft server behind the proxy. With the feature enabled the PlayerResourcePackStatusEvent will be called on a Spigot server even when it is behind a Velocity proxy allowing other plugins to detect that a pack was loaded (or not) without relying on FRP's events. This makes it behave the same way as running FRP on BungeeCord.
Preparations for the 1.21.4 update were done (a version constant and pack format mapping) which might make the update work directly without any additional changes on Spigot and Velocity (BungeeCord will still need an update of the plugin)