Support the monaco editor in flipper and add it to the smax plugin

Summary:
## Context

The editor for mocks is currently just a textarea. It'd be nicer as a monaco editor :D

## Changes
* Add monaco editor
* Change bundler for flipper plugins to allow loading .ttf as `dataurl`
* Resize the input/button for name and save and put them at the top next to each other
* Add a default mock template for when the editor is empty

allow-large-files

Reviewed By: aigoncharov

Differential Revision: D45929635

fbshipit-source-id: 66f3103d073ac630cb41d21f2ce3a7f89e15fed8

desktop/pkg-lib/src/runBuild.tsx

@@ -74,6 +74,9 @@ async function runBuild({
     sourcemap: dev ? 'inline' : 'external',
     minify: !dev,
     plugins: intern ? [resolveFbStubsToFbPlugin] : undefined,
+    loader: {
+      '.ttf': 'dataurl',
+    },
   });
 
   const sourceMapUrl = `${out}.map`;