This commit removes the `Litecoin`, `LtcMode` and `LitecoindMode` members from the main LND `Config` struct. Since only the bitcoin blockchain is now supported, this commit also deprecates the `cfg.Bitcoin.Active` config option.
With this commit we make lnd compatible with the public signet test network.
Creates a Config that initializes the chainregistry struct in the lnd package. Also moves all of chainparams.go to the chainreg package.
