Issue description:
With better diving mod which changed underwater oxygen handling the scuba tank doesn’t fill the air. I asked the author about it and he said compatibility should be added from mekanism’s side.
Here’s the oxygen handling method the author of better diving sent me:

ICapabilityDivingAttributes capability = player.getCapability(CapabilityDivingAttributesProvider.DIVING_ATTRIBUTES, null);
capability.getMaxAir();
capability.getCurrentAir();
capability.setCurrentAir(0);
and
BetterDivingConfig.MODULES.oxygenHandling // only for server

Steps to reproduce:

1. Install both Mekanism and better diving.
   2 .Equip scuba tank and gas mask then go in the water.
2. The tank consumes air, but air bubbles won't be refilled.

Version:
Forge: latest 2847
Mekanism: latest 9.8.2.387 with all modules(tools/generators)

No crash report, the game doesn't crash but simply don't work as intended.

With both of these now on 1.16+ can we look into this again ? e.g. Ability to refill Better Diving tanks in the Electrolytic Separator ?

Feel free to open a request on our feature request repo about the originally requested capability support. In regards to having them get filled in the electrolytic separator I would say that should be done on their end via exposing a capability on their tanks to allow gas and oxygen in them.

So I still stand by filling the tanks would make more sense on their end than ours, but I did a little testing and made a small tweak which seems at least in 1.16 to fix filling the player's breath bar when under water without having to do any capability checks.

Closing this at least for now, as the mod in question has not been updated to 1.15 yet and is still only on 1.12.