fix: separate nchainz config/chains and config/paths

[michaelfig]

This is needed to work with changes from #406.

FWIW, you can test nchainz just by running:

$ scripts/nchainz init skip
[... a bunch of output]
Creating light client for ibc0 (gaiad)...
Key cosmos1796deuy9gkhx4xn7lcnvvz7a5w4qn4dwhdes2g imported from ibc1 to relayer...
Creating light client for ibc1 (gaiad)...
ibc0 light client initialized (try=1)
ibc1 light client initialized (try=1)
added path path-0...
Waiting for clients (Control-C to exit)...
path-0 tx conn initialized (try=14)
===============================
=== All connections initialized
I[2021-02-04|12:05:02.693] ★ Connection created: [ibc0]client{07-tendermint-0}conn{connection-0} -> [ibc1]client{07-tendermint-0}conn{connection-0} 
===============================

and then will stop until interrupted with Control-C.

[colin-axner]

thanks @michaelfig!! It slipped my mind to test it