Make FluidPrototype implement fuel_category

[pastelstoic]

A few recent changes made it so the fuel_value field on fluids is more supported, such as allowing fusion-generator to use it. However, this causes problems with any machine that allows any fluid, such as the K2 gas power generators.

Adding a fuel category to fluids, defaulting to "default" to not be a breaking change, would let mods using the fuel_value field keep to themselves unless specifically made compatible. FluidEnergySource, FusionGenerator, and Generator would also need a fuel_categories field (also optional, defaulting to {"default"}). Any fluid not in that category would act as if it had no fuel value, and destroy_non_fuel_fluid would operate as expected.

[protocol_1903]

This would be a much more interesting take on the 'allow fluid filters' request, I like it. +1

[MrSmoothieHuman]

+1, literally have been wanting this for over a year for things like fuel-powered generators