lncfg+lnd: add new dev config unsafeconnect

This flag is added so we can use it in the itest to mimic racing inbound
and outbound connections.

lncfg/dev.go

@@ -52,3 +52,9 @@ func (d *DevConfig) GetZombieSweeperInterval() time.Duration {
 func (d *DevConfig) GetMaxWaitNumBlocksFundingConf() uint32 {
 	return DefaultMaxWaitNumBlocksFundingConf
 }
+
+// GetUnsafeConnect returns the config value `UnsafeConnect`, which is always
+// false for production build.
+func (d *DevConfig) GetUnsafeConnect() bool {
+	return false
+}