Move app/src (mostly) to flipper-ui-core/src

Summary:
This diff moves all UI code from app/src to app/flipper-ui-core. That is now slightly too much (e.g. node deps are not removed yet), but from here it should be easier to move things out again, as I don't want this diff to be open for too long to avoid too much merge conflicts.

* But at least flipper-ui-core is Electron free :)
* Killed all cross module imports as well, as they where now even more in the way
* Some unit test needed some changes, most not too big (but emotion hashes got renumbered in the snapshots, feel free to ignore that)
* Found some files that were actually meaningless (tsconfig in plugins, WatchTools files, that start generating compile errors, removed those

Follow up work:
* make flipper-ui-core configurable, and wire up flipper-server-core in Electron instead of here
* remove node deps (aigoncharov)
* figure out correct place to load GKs, plugins, make intern requests etc., and move to the correct module
* clean up deps

Reviewed By: aigoncharov

Differential Revision: D32427722

fbshipit-source-id: 14fe92e1ceb15b9dcf7bece367c8ab92df927a70

desktop/flipper-ui-core/src/chrome/fb-stubs/PluginInfo.tsx

@@ -0,0 +1,52 @@
+/**
+ * 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 React from 'react';
+import {useSelector} from 'react-redux';
+import {getActivePlugin} from '../../selectors/connections';
+import {ActivePluginListItem} from '../../utils/pluginUtils';
+import {Layout} from '../../ui';
+import {CenteredContainer} from '../../sandy-chrome/CenteredContainer';
+import {Typography} from 'antd';
+import {PluginActions} from '../PluginActions';
+import {CoffeeOutlined} from '@ant-design/icons';
+
+const {Text, Title} = Typography;
+
+export function PluginInfo() {
+  const activePlugin = useSelector(getActivePlugin);
+  if (activePlugin) {
+    return <PluginMarketplace activePlugin={activePlugin} />;
+  } else {
+    return null;
+  }
+}
+
+function PluginMarketplace({
+  activePlugin,
+}: {
+  activePlugin: ActivePluginListItem;
+}) {
+  return (
+    <CenteredContainer>
+      <Layout.Container center gap style={{maxWidth: 350}}>
+        <CoffeeOutlined style={{fontSize: '24px'}} />
+        <Title level={4}>
+          Plugin '{activePlugin.details.title}' is {activePlugin.status}
+        </Title>
+        {activePlugin.status === 'unavailable' ? (
+          <Text style={{textAlign: 'center'}}>{activePlugin.reason}.</Text>
+        ) : null}
+        <Layout.Horizontal gap>
+          <PluginActions activePlugin={activePlugin} type="link" />
+        </Layout.Horizontal>
+      </Layout.Container>
+    </CenteredContainer>
+  );
+}

desktop/flipper-ui-core/src/chrome/fb-stubs/SignInSheet.tsx

@@ -0,0 +1,14 @@
+/**
+ * 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
+ */
+
+export async function showLoginDialog(
+  _initialToken: string = '',
+): Promise<boolean> {
+  return false;
+}