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/utils/screenshot.tsx

@@ -0,0 +1,66 @@
+/**
+ * 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 fs from 'fs';
+import path from 'path';
+import BaseDevice from '../devices/BaseDevice';
+import {reportPlatformFailures} from 'flipper-common';
+import expandTilde from 'expand-tilde';
+import config from '../utils/processConfig';
+import {getRenderHostInstance} from '../RenderHost';
+
+export function getCaptureLocation() {
+  return expandTilde(
+    config().screenCapturePath || getRenderHostInstance().paths.desktopPath,
+  );
+}
+
+// TODO: refactor so this doesn't need to be exported
+export function getFileName(extension: 'png' | 'mp4'): string {
+  // Windows does not like `:` in its filenames. Yes, I know ...
+  return `screencap-${new Date().toISOString().replace(/:/g, '')}.${extension}`;
+}
+
+export async function capture(device: BaseDevice): Promise<string> {
+  if (!device.connected.get()) {
+    console.log('Skipping screenshot for disconnected device');
+    return '';
+  }
+  const pngPath = path.join(getCaptureLocation(), getFileName('png'));
+  return reportPlatformFailures(
+    device.screenshot().then((buffer) => writeBufferToFile(pngPath, buffer)),
+    'captureScreenshot',
+  );
+}
+
+/**
+ * Writes a buffer to a specified file path.
+ * Returns a Promise which resolves to the file path.
+ */
+export const writeBufferToFile = (
+  filePath: string,
+  buffer: Buffer,
+): Promise<string> => {
+  return new Promise((resolve, reject) => {
+    fs.writeFile(filePath, buffer, (err) => {
+      if (err) {
+        reject(err);
+      } else {
+        resolve(filePath);
+      }
+    });
+  });
+};
+
+/**
+ * Creates a Blob from a Buffer
+ */
+export const bufferToBlob = (buffer: Buffer): Blob => {
+  return new Blob([buffer]);
+};