lncfg: add IsLocalNetwork helper

It returns true for Signet and Regtest networks.

chainreg/chainregistry.go

@@ -528,7 +528,7 @@ func NewPartialChainControl(cfg *Config) (*PartialChainControl, func(), error) {
 			// On local test networks we usually don't have multiple
 			// chain backend peers, so we can skip
 			// the checkOutboundPeers test.
-			if cfg.Bitcoin.SimNet || cfg.Bitcoin.RegTest {
+			if cfg.Bitcoin.IsLocalNetwork() {
 				return nil
 			}
 
@@ -651,7 +651,7 @@ func NewPartialChainControl(cfg *Config) (*PartialChainControl, func(), error) {
 			// On local test networks we usually don't have multiple
 			// chain backend peers, so we can skip
 			// the checkOutboundPeers test.
-			if cfg.Bitcoin.SimNet || cfg.Bitcoin.RegTest {
+			if cfg.Bitcoin.IsLocalNetwork() {
 				return nil
 			}
 

lncfg/chain.go

@@ -52,3 +52,9 @@ func (c *Chain) Validate(minTimeLockDelta uint32, minDelay uint16) error {
 
 	return nil
 }
+
+// IsLocalNetwork returns true if the chain is a local network, such as
+// simnet or regtest.
+func (c *Chain) IsLocalNetwork() bool {
+	return c.SimNet || c.RegTest
+}