[Feature Request] Mobs with nametags should not be hidden

[lumenoxs]

In some circumstances a nametagged mob/player would be partially visible (e.g. their nametag) even while behind solid blocks

There should be a check as to whether a mob has a nametag and is in the players vision, and is of a close enough distance to be visible

[Cubicake]

This can be an extension to the metadata packet partial parsing, with the result stored on one of the 6 remaining free bits in NettyEntity.