Figure out webpack-stats.json

[smcalilly]

Description

Is webpack-stats.json supposed to be committed to version control or not?

Docs say no.

Our experience says otherwise.

We need to configure our setup so we don't need this file in version control.

[hancush]

django-webpack-loader requires us to specify where the webpack-stats.json file lives, and complains if it doesn't exist (e.g., at build time if we haven't committed that file to version control). https://github.com/django-webpack/django-webpack-loader?tab=readme-ov-file#configuring-the-django-settings-file

to circumvent this, we can use the dummy loader they provide in our tests: https://github.com/django-webpack/django-webpack-loader?tab=readme-ov-file#using-in-tests

[antidipyramid]

Will be handled in #371