htlcswitch: add InterceptableSwitchConfig

Preparation for adding more config options.

htlcswitch/switch_test.go

@@ -3846,7 +3846,10 @@ func TestSwitchHoldForward(t *testing.T) {
 		interceptedChan: make(chan InterceptedPacket),
 	}
 	switchForwardInterceptor := NewInterceptableSwitch(
-		s, cltvRejectDelta, false,
+		&InterceptableSwitchConfig{
+			Switch:          s,
+			CltvRejectDelta: cltvRejectDelta,
+		},
 	)
 	require.NoError(t, switchForwardInterceptor.Start())
 
@@ -4037,7 +4040,13 @@ func TestSwitchHoldForward(t *testing.T) {
 	require.NoError(t, switchForwardInterceptor.Stop())
 
 	// Test always-on interception.
-	switchForwardInterceptor = NewInterceptableSwitch(s, cltvRejectDelta, true)
+	switchForwardInterceptor = NewInterceptableSwitch(
+		&InterceptableSwitchConfig{
+			Switch:             s,
+			CltvRejectDelta:    cltvRejectDelta,
+			RequireInterceptor: true,
+		},
+	)
 	require.NoError(t, switchForwardInterceptor.Start())
 
 	// Forward a fresh packet. It is expected to be failed immediately,
@@ -5329,7 +5338,11 @@ func testSwitchAliasInterceptFail(t *testing.T, zeroConf bool) {
 		t:               t,
 		interceptedChan: make(chan InterceptedPacket),
 	}
-	interceptSwitch := NewInterceptableSwitch(s, 0, false)
+	interceptSwitch := NewInterceptableSwitch(
+		&InterceptableSwitchConfig{
+			Switch: s,
+		},
+	)
 	require.NoError(t, interceptSwitch.Start())
 	interceptSwitch.SetInterceptor(forwardInterceptor.InterceptForwardHtlc)