Remove redundent typings

src/typings/react-app-env.d.ts

-/// <reference types="react-scripts" />

src/typings/scss.d.ts

-// scss.d.ts
-declare module "*.css" {
-    const content: { [className: string]: string };
-    export default content;
-}
-
-declare module "*.scss" {
-    const content: { [className: string]: string };
-    export default content;
-}