add initial Angular components, services, and routing setup

client/src/app/interfaces/credentials/credentials.spec.ts

@@ -0,0 +1,7 @@
+import { Credentials } from './credentials';
+
+describe('Credentials', () => {
+  it('should create an instance', () => {
+    expect(new Credentials()).toBeTruthy();
+  });
+});

client/src/app/interfaces/credentials/credentials.ts

@@ -0,0 +1,4 @@
+export interface Credentials {
+  username: string;
+  password: string;
+}