Add CSS typings

Closes #2195

frontend/src/Bookshelf/Bookshelf.css.d.ts

@@ -0,0 +1,10 @@
+// This file is automatically generated.
+// Please do not change this file!
+interface CssExports {
+  'contentBody': string;
+  'contentBodyContainer': string;
+  'pageContentBodyWrapper': string;
+  'tableInnerContentBody': string;
+}
+export const cssExports: CssExports;
+export default cssExports;