Improve handling of custom fluids in tank renderers

[matelemons]

Description

This PR changes tank renderers to use FluidStack instead of Fluid in order to tint the fluid element. This is because it seems like some mods only override the FluidStack variant of getTintColor (most notably, Create: Dragons Plus and its liquid dyes). As far as I'm aware there's no downside to doing it this way, correct me if I'm wrong.

Before:

After:

Liquid dyes are no longer drawn as white.

How Has This Been Tested?

• Feature has been tested ingame on both neoforge and fabric.
• Tested with Create: Dragons Plus fluids

Checklist:

• My code uses the 'var' keyword where applicable.
• [N/A] I have commented my code, particularly in hard-to-understand areas - N/A, I believe there's no need for extra comments.