Describe the solution you'd like
Currently there are solutions for gaining XP by moving in the Y direction (Surfacing, Diving). There are no events for gaining XP for moving in the X or Z directions. If submerged XP is enabled then XP is granted all the time while underwater, if it is disabled then no xp is granted for moving in the X and Z planes.

Why is this feature needed
To give players XP consistently for swimming in the X and Z planes based on distance moved just like DIVING and SUBMERGED

Describe alternatives you've considered
Give XP Passively just for being underwater, but that doesn't feel good as they're not doing anything to "earn" the xp. Granting XP from movement seems like the best method.

Additional context
This is related to #464. I do still think there is a bug there with surfacing and diving per this issue, but I turned the XP down far enough that it shouldn't matter.

even with 100xp for SUBMERGED, the player simply does not move fast enough to provide a calculatable value. Furthermore, in most cases the player is either sprinting, or is moving ever so slightly up or down, which triggers DIVING/SURFACING respectively instead of submerged. I even gave myself depth strider and a modified movement attribute to try and trigger enough speed to register movement big enough to show up with xp and it had no effect.

I think for your use case, you should use an AFK anti-cheese on SUBMERGED so that moving disables the anti-cheese and resumes the XP, but sitting still gives nothing.