Handle different environment cases for different builds

[sandiprb]

To handle cases where webpack produces a vendor, manifest etc. files which are required in
the production config but is not produced in the dev environment.

A primary example of this can be projects generated by Vue CLI.

[sandiprb]

@ranedk Raising this PR here since I feel this feature helps a lot.

[owais]

I personally think such things should be put under an if clause inside the template. Pseudo code:

if is_production:
    load(manifest)
load(assets)

[owais]

But if you really want the template tag, it could easily live in your django project. I don't think it's important enough to live in the core package. Closing but happy to hear your thoughts.