Complete crafting jobs on networks without discretizer

[Demiu]

Allows for this:

Only red network has the discretizer.

Previously, without a discretizer in the green network you could start jobs, but fluid products were never registered in crafting. Discretizer was a dual-purpose block. The item inventory (FluidDiscretizingInventory) provided droplet representations of fluids in the network + conversion on droplet inject/extract. The fluid inventory (FluidCraftingInventory) converted injected fluids to droplets and attempted to inject them into the crafting grid.

This PR replaces the CraftingGridCache::getCellArray function responsible for getting the inventory handlers which are part of StorageGrid. On channel ITEMS there is no functional change, on channel FLUIDS instead of nothing it now returns a proxy to the CraftingGridCache which performs the same work as discretizer's fluid inventory (conversion to fluid and back).
As a bonus with no need for second discretizer the droplets no longer need to be doubled on green net.

The FluidDiscretizingInventory of discretizer is still needed
FluidCraftingInventory and FluidCraftingInventoryHandler of discretizer I think could be removed

Removed some static methods in CoreModHooks which were unused