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/patches/adbkit+2.11.1.patch

@@ -0,0 +1,47 @@
+diff --git a/node_modules/adbkit/lib/adb/parser.js b/node_modules/adbkit/lib/adb/parser.js
+index 1b66bda..c41037d 100644
+--- a/node_modules/adbkit/lib/adb/parser.js
++++ b/node_modules/adbkit/lib/adb/parser.js
+@@ -52,7 +52,7 @@ Parser = (function() {
+ 
+   Parser.prototype.readAll = function() {
+     var all, endListener, errorListener, resolver, tryRead;
+-    all = new Buffer(0);
++    all = Buffer.alloc(0);
+     resolver = Promise.defer();
+     tryRead = (function(_this) {
+       return function() {
+@@ -108,7 +108,7 @@ Parser = (function() {
+             return resolver.reject(new Parser.PrematureEOFError(howMany));
+           }
+         } else {
+-          return resolver.resolve(new Buffer(0));
++          return resolver.resolve(Buffer.alloc(0));
+         }
+       };
+     })(this);
+@@ -196,7 +196,7 @@ Parser = (function() {
+ 
+   Parser.prototype.readUntil = function(code) {
+     var read, skipped;
+-    skipped = new Buffer(0);
++    skipped = Buffer.alloc(0);
+     read = (function(_this) {
+       return function() {
+         return _this.readBytes(1).then(function(chunk) {
+diff --git a/node_modules/adbkit/lib/adb/protocol.js b/node_modules/adbkit/lib/adb/protocol.js
+index d1377d0..2edd7ba 100644
+--- a/node_modules/adbkit/lib/adb/protocol.js
++++ b/node_modules/adbkit/lib/adb/protocol.js
+@@ -33,9 +33,9 @@ Protocol = (function() {
+ 
+   Protocol.encodeData = function(data) {
+     if (!Buffer.isBuffer(data)) {
+-      data = new Buffer(data);
++      data = Buffer.from(data);
+     }
+-    return Buffer.concat([new Buffer(Protocol.encodeLength(data.length)), data]);
++    return Buffer.concat([Buffer.from(Protocol.encodeLength(data.length)), data]);
+   };
+ 
+   return Protocol;