clightning: add netns

- Adds clightning to netns-isolation.services
- Adds bitcoin-rpcconnect option to allow using clightning with network
  namespaces
- Uses bind-addr option (defaults to localhost) as target of hidden service
- Adds different bind-addr options depending on if netns-isolation is
  enabled or not.

modules/clightning.nix

@@ -12,6 +12,7 @@ let
     ${optionalString (cfg.proxy != null) "proxy=${cfg.proxy}"}
     always-use-proxy=${if cfg.always-use-proxy then "true" else "false"}
     ${optionalString (cfg.bind-addr != null) "bind-addr=${cfg.bind-addr}"}
+    ${optionalString (cfg.bitcoin-rpcconnect != null) "bitcoin-rpcconnect=${cfg.bitcoin-rpcconnect}"}
     bitcoin-rpcuser=${config.services.bitcoind.rpcuser}
     rpc-file-mode=0660
   '';
@@ -54,6 +55,11 @@ in {
       default = false;
       description = "Announce clightning Tor Hidden Service";
     };
+    bitcoin-rpcconnect = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+      description = "The bitcoind RPC host to connect to.";
+    };
     dataDir = mkOption {
       type = types.path;
       default = "/var/lib/clightning";