Move VPN Resource Center images from Contentful CDN to Bedrock media

[stevejalim]

Do not merge for now.

One-line summary

This changeset moves the VPN RC away from using images live-hosted by Contentful.

It:

• adds all of the images, in the appropriate size, from the Contentful CDN to our bedrock codebase
• contains a data migration that, when run, updates the contentful_contentfulentry table appropriately. (It swaps the src and/or srcset attributes of img tags from full Contentful CDN URLs to local image paths instead, matching the files added to the codebase.
• EDIT: stops the regular syncing of Contentful content, else a change (or a forced update on Dev or a Demo) would overwrite the changes to use the local files

Significant changes and points to review

The data migration is not pretty, but should make sense. Please call out anything that looks too strange.

Issue / Bugzilla link

No ticket

Testing

Locally:

• on main run ./bin/run-db-download.py --force
• switch to this branch
• ./manage.py migrate which should apply one migration (0007) in the contentful app
• Go to http://localhost:8000/en-US/products/vpn/resource-center/
  • Confirm there are no missing images, broken HTML, etc and that images are loaded from localhost not https://images.ctfassets.net
  • View each child page and confirm all OK and loading local images - having the Network tab in Devtools helps
  • When a child page contains an image, use devtools to drop the DPR from 2 to 1 and confirm via the Network tab that the lower-res image is loaded, and that it's locally sourced

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.10%. Comparing base (7acd730) to head (10a6262).

❗ Current head 10a6262 differs from pull request most recent head e48c310. Consider uploading reports for the commit e48c310 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #14198      +/-   ##
==========================================
+ Coverage   76.60%   77.10%   +0.50%     
==========================================
  Files         144      145       +1     
  Lines        7818     7894      +76     
==========================================
+ Hits         5989     6087      +98     
+ Misses       1829     1807      -22     

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[alexgibson]

I tested this locally and things seem to work as expected 👍

I did notice a lot of the images are quite large, and we can save between 60% and 80% in file size by running things through tinypng. It would be nice to do that before merging?

[stevejalim]

@alexgibson Images optimised in 88d155b - thanks for the reminder!

[stevejalim]

Marking this as Do Not Merge, but could still do with a final review. It's ready to roll, but we may as well leave it until later in case we need to edit any copy. If we change images, this PR would need updating, but not copy changes.

[alexgibson]

r++