mutli: rename HodlEvent to HtlcResolution

This commit renames HodlEvent to HtlcResolution
to better reflect the fact that the struct is
only used for htlc settles and cancels, and that
it is not specifically used for hodl invoices.

htlcswitch/interfaces.go

@@ -27,7 +27,7 @@ type InvoiceDatabase interface {
 	NotifyExitHopHtlc(payHash lntypes.Hash, paidAmount lnwire.MilliSatoshi,
 		expiry uint32, currentHeight int32,
 		circuitKey channeldb.CircuitKey, hodlChan chan<- interface{},
-		payload invoices.Payload) (*invoices.HodlEvent, error)
+		payload invoices.Payload) (*invoices.HtlcResolution, error)
 
 	// CancelInvoice attempts to cancel the invoice corresponding to the
 	// passed payment hash.
@@ -36,7 +36,7 @@ type InvoiceDatabase interface {
 	// SettleHodlInvoice settles a hold invoice.
 	SettleHodlInvoice(preimage lntypes.Preimage) error
 
-	// HodlUnsubscribeAll unsubscribes from all hodl events.
+	// HodlUnsubscribeAll unsubscribes from all htlc resolutions.
 	HodlUnsubscribeAll(subscriber chan<- interface{})
 }