Grey icon for PWA

Summary:
Right now, both Launcher and PWA share the same icon.

As to make it easier to identify which one is which, PWA will have a greyed icon instead.

Reviewed By: antonk52

Differential Revision: D47436998

fbshipit-source-id: 69d4d273c35e327263fbbf02d4ac7a005013f1d9

desktop/scripts/build-flipper-server-release.tsx

@@ -228,6 +228,7 @@ async function copyStaticResources(outDir: string, versionNumber: string) {
     'icon.icns',
     'icon.ico',
     'icon.png',
+    'icon_grey.png',
     'icons.json',
     'index.web.dev.html',
     'index.web.html',

desktop/static/manifest.template.json

@@ -10,7 +10,7 @@
     "orientation": "portrait-primary",
     "icons": [
       {
-        "src": "/icon.png",
+        "src": "/icon_grey.png",
         "type": "image/png",
         "sizes": "256x256"
       }