[WIP] Editor resource browser & right click menus

Do not merge just yet.  This is still a work in progress.

I have added via brute force a mechanism which scans each file in the resourceDirs.  It checks the binary signature/xml root if it can and falls back to file extensions for some meaningful cases.  It is honestly really hard to account for every possibility the browser can handle.  I would like some opinions on how it can be improved without having to change too much about it.  I would also understand if this is rejected because of code impact.

The resource browser items can be dragged into the hierarchy in many cases.  I chose to not instance a node to put components in.  These things are naturally to debate.  You can drag prefabs and materials into the viewport.  You can right click on both the hierarchy and browser items to get a context menu.  There are lots of missing integrations I am sure.

Potential Issues
- The file scanning can produce errors.  A mechanism for silencing logs would be useful during scanning.
Known Bugs
- Opacity of the file list isn't the right color.
- The drag cursor isn't right for dragging file items into the viewport.

I will do a pass to fix the issues with the coding guidelines.  I would like to get opinions on this beast and get it up to snuff!  When I worked in master I missed the browser.  Hopefully others will like it.

:heart: :heart: 
Chris