core,app: add a method for registering APIs

packages/app/src/App.tsx

@@ -20,6 +20,7 @@ import React, { FC } from 'react';
 import { BrowserRouter as Router } from 'react-router-dom';
 import Root from './components/Root';
 import * as plugins from './plugins';
+import apis from './apis';
 
 const useStyles = makeStyles(theme => ({
   '@global': {
@@ -40,6 +41,7 @@ const useStyles = makeStyles(theme => ({
 }));
 
 const app = createApp();
+app.registerApis(apis);
 app.registerPlugin(...Object.values(plugins));
 const AppComponent = app.build();
 

packages/app/src/apis.ts

@@ -0,0 +1,21 @@
+/*
+ * Copyright 2020 Spotify AB
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { ApiHolder, ApiRegistry } from '@spotify-backstage/core';
+
+const builder = ApiRegistry.builder();
+
+export default builder.build() as ApiHolder;