Dependency injection for oas servicemap (#895)

* Update main.go, main.go, and 3 more files...

* WIP

* Update main.go, oas_controller.go, and 3 more files...

* Update main.go, oas_generator.go, and servicemap.go

* Update loader.go and resolver.go

* Update oas_generator.go

* Update oas_generator.go, specgen_test.go, and 3 more files...

* Update service_map_controller_test.go

* Update oas_controller_test.go

agent/pkg/dependency/container.go

@@ -0,0 +1,11 @@
+package dependency
+
+var typeIntializerMap = make(map[DependencyContainerType]func() interface{}, 0)
+
+func RegisterGenerator(name DependencyContainerType, fn func() interface{}) {
+	typeIntializerMap[name] = fn
+}
+
+func GetInstance(name DependencyContainerType) interface{} {
+	return typeIntializerMap[name]()
+}

agent/pkg/dependency/type_names.go

@@ -0,0 +1,8 @@
+package dependency
+
+type DependencyContainerType string
+
+const (
+	ServiceMapGeneratorDependency = "ServiceMapGeneratorDependency"
+	OasGeneratorDependency        = "OasGeneratorDependency"
+)