Add complete test scaffolding support with --test flag for API projects (#5176)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: kevwan <1918356+kevwan@users.noreply.github.com>

tools/goctl/api/gogen/template.go

@@ -22,6 +22,8 @@ const (
 	routesTemplateFile          = "routes.tpl"
 	routesAdditionTemplateFile  = "route-addition.tpl"
 	typesTemplateFile           = "types.tpl"
+	svcTestTemplateFile         = "svc_test.tpl"
+	integrationTestTemplateFile = "integration_test.tpl"
 )
 
 var templates = map[string]string{
@@ -39,6 +41,8 @@ var templates = map[string]string{
 	routesTemplateFile:          routesTemplate,
 	routesAdditionTemplateFile:  routesAdditionTemplate,
 	typesTemplateFile:           typesTemplate,
+	svcTestTemplateFile:         svcTestTemplate,
+	integrationTestTemplateFile: integrationTestTemplate,
 }
 
 // Category returns the category of the api files.