Use one webpack build for pro and blocks

[Shelob9]

I tried to get edit and admin into webpack, too much stuff breaks. It's going to need more work or a rewrite.

This PR uses one webpack config to build pro admin ui and blocks. It leaves a place for admin and entry view clients.

Resolves:
#2167

TODO:

• Update build script to include production parts.
• Consider moving files back to where they originally where during build

Out of scope:

• Rebuilding admin page (some of this work got started) Rebuild main admin page #2445
• Rebuilding form editor
• Moving entry viewer to new webpack build system Move entry viewer to new webpack build system #2446
• composer depenendencies (pro uses some, would like to use more.) Move composer dependencies from pro to main composer.json and use composer autoloader #2447