GitHub Action CI: Add Go source file format check (#6090)

https://github.com/XTLS/Xray-core/pull/6057#issuecomment-4364819830

And https://github.com/XTLS/Xray-core/pull/6149#issuecomment-4546876261

app/proxyman/outbound/handler.go

@@ -348,7 +348,7 @@ func (h *Handler) SetOutboundGateway(ctx context.Context, ob *session.Outbound)
 					errors.LogDebug(ctx, "use inbound source ip as sendthrough: ", inbound.Source.Address.String())
 				}
 			}
-		//case addr.Family().IsDomain():
+		// case addr.Family().IsDomain():
 		default:
 			ob.Gateway = addr
 
@@ -396,7 +396,6 @@ func (h *Handler) ProxySettings() *serial.TypedMessage {
 }
 
 func ParseRandomIP(addr net.Address, prefix string) net.Address {
-
 	_, ipnet, _ := net.ParseCIDR(addr.IP().String() + "/" + prefix)
 
 	ones, bits := ipnet.Mask.Size()

app/proxyman/outbound/handler_test.go

@@ -22,8 +22,8 @@ import (
 )
 
 func TestInterfaces(t *testing.T) {
-	_ = (outbound.Handler)(new(Handler))
-	_ = (outbound.Manager)(new(Manager))
+	_ = outbound.Handler(new(Handler))
+	_ = outbound.Manager(new(Manager))
 }
 
 const xrayKey core.XrayKey = 1
@@ -43,7 +43,7 @@ func TestOutboundWithoutStatCounter(t *testing.T) {
 	}
 
 	v, _ := core.New(config)
-	v.AddFeature((outbound.Manager)(new(Manager)))
+	v.AddFeature(outbound.Manager(new(Manager)))
 	ctx := context.WithValue(context.Background(), xrayKey, v)
 	ctx = session.ContextWithOutbounds(ctx, []*session.Outbound{{}})
 	h, _ := NewHandler(ctx, &core.OutboundHandlerConfig{
@@ -73,7 +73,7 @@ func TestOutboundWithStatCounter(t *testing.T) {
 	}
 
 	v, _ := core.New(config)
-	v.AddFeature((outbound.Manager)(new(Manager)))
+	v.AddFeature(outbound.Manager(new(Manager)))
 	ctx := context.WithValue(context.Background(), xrayKey, v)
 	ctx = session.ContextWithOutbounds(ctx, []*session.Outbound{{}})
 	h, _ := NewHandler(ctx, &core.OutboundHandlerConfig{
@@ -88,7 +88,6 @@ func TestOutboundWithStatCounter(t *testing.T) {
 }
 
 func TestTagsCache(t *testing.T) {
-
 	test_duration := 10 * time.Second
 	threads_num := 50
 	delay := 10 * time.Millisecond

app/proxyman/outbound/outbound.go

@@ -162,7 +162,6 @@ func (m *Manager) ListHandlers(ctx context.Context) []outbound.Handler {
 
 // Select implements outbound.HandlerSelector.
 func (m *Manager) Select(selectors []string) []string {
-
 	key := strings.Join(selectors, ",")
 	if cache, ok := m.tagsCache.Load(key); ok {
 		return cache.([]string)