Who is Mulch Diggums from Artemis Fowl: The Lost Colony and what is their importance?

Mulch Diggums is a dwarf. Once a criminal, he is now Holly's business partner. Dwarfs are described to be like gophers..... digging under the ground and living on the dirt and stuff they get out of their holes. Mulch assists Artemis and Holly by getting Doodah Day close to the Paradizo property, so Doodah could plant a fiber optic cable, which would allow Holly and Foaly access to the security system in Minerva's house.