Allow overriding AluminumBrass as the metal pattern material

[YannickMG]

Adds a config to exchange AluminumBrass for another FluidType register with TiCo during the pre-init phase.

Needed to use GT brass instead of TiCo AluminumBrass in the modpack. I plan to register the FluidType in Dreamcraft.

Also includes some code cleanup which helped me make sure I didn't miss a recipe.

Sample usage

crossmodinteractions {
    # For pack maintainers. Defines the LiquidType used to create metal casts.
    S:"Metal cast FluidType"=Aluminum
}