Multiple nodes

[JssDWt]

Allow lspd to 'host' multiple nodes.

• Every lightning node is its own 'lsp', so every node has a unique lsp key and a (important) corresponding token. In theory the lsp key could be the same on multiple nodes, but the token definitely has to differ (there's a check for that in the code as well, you can't launch lspd if you have multiple nodes configured with the same token.
• When calls are made over the grpc api (register payment / channel information), the 'right' node is selected based on the token. So LND Breez clients should end up using the LND node lsp's token in order to register the payment on the 'right' node.
• The .env config has changed to allow multiple nodes (you could add multiple LND/CLN nodes as well if you want)