Reduce Manager JS HTTP Requests

this PR does two things
*  mimicks the job of groupsConfig.php via `grunt build`
* reduces HTTP Requests for Manager JS

while not reliant upon, assumes PR modxcms/revolution#11526 is merged
because it packages files accordingly (so please review that PR first)

`grunt build`
now concats and minifies the manger JS into three pairs of minified and
un-minified files.

keeping it broken apart in three for legacy reasons. ultimately
probably should be packed into one modext/jsgrp.js file

will likely submit a separate but dependent PR that packs them all in
one

Not there are grunt dependencies added so remember to
```bash
cd revolution/build/templates/default
npm install
grunt build
```