Introduce PluginRenderer to render plugins

Summary: PluginContainer will now wrap Sandy plugins in PluginRenderer. PluginRenderer will also be used by plugin unit tests in the future

Reviewed By: jknoxville

Differential Revision: D22159359

fbshipit-source-id: 69f9c8f4bec9392022c1d7a14957f5aca0339d97

desktop/flipper-plugin/src/plugin/PluginContext.tsx

@@ -0,0 +1,23 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+import {createContext} from 'react';
+
+export type SandyPluginContext = {
+  deactivate(): void;
+};
+
+// TODO: to be filled in later with testing and such
+const stubPluginContext: SandyPluginContext = {
+  deactivate() {},
+};
+
+export const SandyPluginContext = createContext<SandyPluginContext>(
+  stubPluginContext,
+);