[Suggestion] Custom player info forwarding mode

It would be helpful to include a CUSTOM enum value in PlayerInfoForwarding, which would do nothing and leave the UUIDs alone.
Here's the context:

I've been developing a custom player info forwarding system for my server network, using both a Velocity plugin and Spigot plugin.
I was able to get everything working, but I had one issue with the Velocity proxy:

Line 135 of the AuthSessionHandler changes the player's UUID to the offline version when the forwarding mode is set to none.
This made it so the player couldn't see their own skin, and the chat messages weren't signed properly, as the server expected the player to have their real UUID.

I was able to avoid this issue by compiling the PlayerInfoForwarding file with an additional CUSTOM entry. I could then copy this modified file into the normal velocity.jar, and change the config option to CUSTOM.
This left the UUIDs alone, allowing the system to work properly.

Having this enum value be a part of the proxy itself by default would be more convenient.
Thanks!

Start with the PlayerInfoForwarding enum and AuthSessionHandler around line 135, where the issue reports that NONE changes the player's UUID. Add and verify the requested CUSTOM mode so UUIDs remain unchanged, then check the proxy behavior against the custom forwarding setup described in the issue.