Test node for the devnet environment

Implement a test node which can be used a single node, but functions as network by itself to be used with DevNet. 
The node should contain the Sygma substrate pallet and have the assets and MPC address setup from the DevNet environment. 
It should expose the same RPC API as the Phala/Rhala/Tangle nodes.

@eedygreen to consult on how to best deploy it.