Move plugins to "sonar/desktop/plugins"

Summary:
Plugins moved from "sonar/desktop/src/plugins" to "sonar/desktop/plugins".

Fixed all the paths after moving.

New "desktop" folder structure:
- `src` - Flipper desktop app JS code executing in Electron Renderer (Chrome) process.
- `static` - Flipper desktop app JS code executing in Electron Main (Node.js) process.
- `plugins` - Flipper desktop JS plugins.
- `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 desktop app.
- `headless-tests` - Integration tests running agains Flipper headless version.

Reviewed By: mweststrate

Differential Revision: D20344186

fbshipit-source-id: d020da970b2ea1e001f9061a8782bfeb54e31ba0

desktop/plugins/kaios-allocations/patches/firefox-client+0.3.0.patch

@@ -0,0 +1,13 @@
+diff --git a/node_modules/firefox-client/lib/client.js b/node_modules/firefox-client/lib/client.js
+index 22b3179..11e8d7f 100644
+--- a/node_modules/firefox-client/lib/client.js
++++ b/node_modules/firefox-client/lib/client.js
+@@ -2,8 +2,6 @@ var net = require("net"),
+     events = require("events"),
+     extend = require("./extend");
+ 
+-var colors = require("colors");
+-
+ module.exports = Client;
+ 
+ // this is very unfortunate! and temporary. we can't