added AuthInterceptor for sending api key in the header on every request to api

src/app/http-interceptors/index.ts

@@ -0,0 +1,7 @@
+import { HTTP_INTERCEPTORS } from "@angular/common/http";
+
+import { AuthInterceptor } from "./auth.interceptor";
+
+export const httpInterceptorProviders = [
+    {provide: HTTP_INTERCEPTORS, useClass: AuthInterceptor, multi: true}
+]