Decouple L2 node from protocol PVM signature

Decouple the L2 node from the protocol's PVM implementations. This allows us to extend the interface of a PVM with functions that are useful in the L2 node but not in the protocol. The current state is that the L2 node depends entirely on the PVM signature and implemention from the protocol. Visually this is L2 node -> protocol -> protocol environment -> lib_scoru_wasm. Because the PVMs pass through the narrowed down interface of the protocol and its environment, additional functions would be lost. Circumventing this allows us to add functions, without the protocol interfering with them.