UI 2.0: Create Build Pipeline for Core (Generates UI on startup/post-upgrade)

[bryanculver]

This translates as hiding npm behind a management command (e.g. nautobot-server build) and then having it as something that can then be called by other commands such as post_upgrade. (See similar example from NSoT project embedding this into setup.py build: https://github.com/dropbox/nsot/blob/develop/setup.py#L66-L90)

Webpack should be configured to deploy files to the STATICFILES_DIRS which defaults to project-static in the js directory? (See: https://pascalw.me/blog/2020/04/19/webpack-django.html):

1. Have Webpack write to a directory in STATICFILES_DIRS
2. Configure output.publicPath to match Django's STATIC_URL
3. Don't let Webpack hash filenames (except for chunks, see below)
4. Make sure webpack-dev-server writes files to disk (so Django can serve them in development)

Tasks

Beta Give feedback

1. Create new build management command
2. Configure web pack to deploy bundles to project-static/js
3. Assert that build is called by post_upgrade

[bryanculver]

Closed with #3306