Fix editor image routing

[ahukkanen]

🎩 What? Why?

While implementing #12576, there was one problem regarding the blob URLs that are persisted to the database which is that they cannot be created dynamically at render time because the HTML is persisted to the database as-is.

This fixes the issue by replacing references to any blob URLs with the blob's global ID and then swapping it back to the actual URL when these values are rendered.

This fixes two issues:

1. The blob URLs can be represented in more performant way referencing the direct storage URLs as described at Improve ActiveStorage asset linking performance #12576
2. The blob URLs should not expire if they are stored to the database in a timely manner (i.e. within 7 days from creation)

This also changes the signed blob URL expiry period to 7 days which is the maximum set by Amazon S3 and Google Cloud Files. This has to be used together with a sensible caching strategy as the expiry periods of these 3rd party services cannot be extended. In other words, when using Amazon S3 or Google Cloud Files, the cache has to be cleared at least once every 7 days because e.g. the content block cache is set to expire never.

📌 Related Issues

Link your PR to an issue

• Related to Improve ActiveStorage asset linking performance #12576
• Fixes Expiration time in URL attachments #10028

Testing

• Edit some content that has rich text editor, e.g. a static page
• Embed an image to the content
• Save the form
• See the rich text content value in the database, you should now see the image src attribute replaced with gid://decidim-development-app/ActiveStorage::Blob/XYZ (where XYZ is the blob ID in the database)
• Go to see the page at the participant-facing view
• See that the image is rendered correctly

[ahukkanen]

Note that this PR depends on #12576 which needs to be merged first.

This PR needs one RSpec matcher added in #12576 which would also fix the Codeclimate issues (telling to remove TODO messages).