Refactor single chain changes

[lmoe]

We removed the capability to deploy multiple chains per node.

The removal was only partially executed. Mainly inside VM/State/WebAPI. However, ChainManager, StateManager and other components still support the option to deploy multiple chains. Their interfaces are written in a way to support multiple chains. Internally they use maps and lists to handle multiple chains, etc..

Deploying multiple chains is currently only impossible because the WebAPI rejects this.

To clean up our code base we should remove all traces related to the multi chain implementation.

The only thing we should keep is the current folder structure:

./waspdb/chains/data/
./waspdb/chains/index/

So we don't have to introduce downtime to our operations when we have to move all databases to another place.