Make TabListEntry have nullable fields

[ghost]

The way addEntry() works, it only sends the appropriate update packet if the fields have changed.

But there is no way to specify you dont want a field to change, if you do TabListEntry.builder() for example, and dont specify gamemode, it defaults to 0, which you'd think means do nothing, but it sends an update packet to set them to survival (gamemode 0),

if it defaulted to null and did no operation it'd be nice as, in my velocity tab list plugin, spectators can't go through walls, since when the tab list updates it sends gamemode 0, and we cant explicitly specify it because on the proxy we don't know what gamemode they should be.

[ghost]

Every velocity tablist plugin has this exact issue, unless they hack in a packet listener to see which gamemode the backend server is telling client they should be