multi: announce Keysend feature bit

In this commit, we add the keysend feature bit to our NodeAnnouncement
if the accept-keysend option is set.

feature/manager.go

@@ -27,6 +27,10 @@ type Config struct {
 	// NoScriptEnforcementLease unsets any bits signaling support for script
 	// enforced leases.
 	NoScriptEnforcementLease bool
+
+	// NoKeysend unsets any bits signaling support for accepting keysend
+	// payments.
+	NoKeysend bool
 }
 
 // Manager is responsible for generating feature vectors for different requested
@@ -83,6 +87,8 @@ func newManager(cfg Config, desc setDesc) (*Manager, error) {
 			raw.Unset(lnwire.MPPRequired)
 			raw.Unset(lnwire.AMPOptional)
 			raw.Unset(lnwire.AMPRequired)
+			raw.Unset(lnwire.KeysendOptional)
+			raw.Unset(lnwire.KeysendRequired)
 		}
 		if cfg.NoStaticRemoteKey {
 			raw.Unset(lnwire.StaticRemoteKeyOptional)
@@ -115,6 +121,10 @@ func newManager(cfg Config, desc setDesc) (*Manager, error) {
 			raw.Unset(lnwire.ScriptEnforcedLeaseOptional)
 			raw.Unset(lnwire.ScriptEnforcedLeaseRequired)
 		}
+		if cfg.NoKeysend {
+			raw.Unset(lnwire.KeysendOptional)
+			raw.Unset(lnwire.KeysendRequired)
+		}
 
 		// Ensure that all of our feature sets properly set any
 		// dependent features.