Move desktop-related code to "desktop" subfolder (#872)

Summary:
Pull Request resolved: https://github.com/facebook/flipper/pull/872
Move all the JS code related to desktop app to "desktop" subfolder.

The structure of "desktop" folder:
- `src` - JS code of Flipper desktop app executing in Electron Renderer (Chrome) process. This folder also contains all the Flipper plugins in subfolder "src/plugins".
- `static` - JS code of Flipper desktop app bootstrapping executing in Electron Main (Node.js) process
- `pkg` - Flipper packaging lib and CLI tool
- `doctor` - Flipper diagnostics lib and CLI tool
- `scripts` - Build scripts for Flipper desktop app
- `headless` - Headless version of Flipper app
- `headless-tests` - Integration tests running agains Flipper headless version

Reviewed By: passy

Differential Revision: D20249304

fbshipit-source-id: 9a51c63b51b92b758a02fc8ebf7d3d116770efe9

desktop/types/adbkit-logcat.d.tsx

@@ -0,0 +1,68 @@
+/**
+ * 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
+ */
+
+// This module declaration is a stub!
+// Please extend this as needed.
+
+declare module 'adbkit-logcat' {
+  type PriorityValue = number;
+
+  interface Reader extends NodeJS.EventEmitter {
+    connect(stream: NodeJS.WriteStream): this;
+    end(): this;
+    exclude(tag: string): this;
+    excludeAll(): this;
+    include(tag: string, priority?: PriorityValue): this;
+    includeAll(priority?: PriorityValue): this;
+    resetFilters(): this;
+
+    on(event: 'error', listener: (err: Error) => void): this;
+    on(event: 'end', listener: () => void): this;
+    on(event: 'finish', listener: () => void): this;
+    on(event: 'entry', listener: (entry: Entry) => void): this;
+  }
+
+  interface Entry {
+    date: Date;
+    pid: number;
+    tid: number;
+    priority: PriorityValue;
+    tag: string;
+    message: string;
+    toBinary(): Buffer;
+  }
+
+  interface Priority {
+    DEBUG: PriorityValue;
+    DEFAULT: PriorityValue;
+    ERROR: PriorityValue;
+    FATAL: PriorityValue;
+    INFO: PriorityValue;
+    SILENT: PriorityValue;
+    UNKNOWN: PriorityValue;
+    VERBOSE: PriorityValue;
+    WARN: PriorityValue;
+
+    fromLetter(letter: string): PriorityValue | undefined;
+    fromName(name: string): PriorityValue | undefined;
+    toLetter(value: PriorityValue): string;
+    toName(value: PriorityValue): string;
+  }
+
+  function readStream(
+    stream: NodeJS.WriteStream,
+    options?: {
+      format: 'binary';
+      fixLineFeeds: boolean;
+    },
+  ): Reader;
+
+  const Priority: Priority;
+  const Reader: Reader;
+}