feat(db-migrations): update content of every entity_revision to new Editor format

[hejtful]

Linear: EDTR-98
Frontend PR: serlo/frontend#4465

Note: Because the new metadata has non-deterministic values, such as dateModified and id, only test for matching document content.

[LarsTheGlidingSquirrel]

Once this ran in staging could you send us an example of the resulting state to verify that everything looks right?

[hejtful]

@LarsTheGlidingSquirrel Thanks for the review, fixed the version!

Could you please explain what you mean by "resulting state"? The content column of a random entity_revision row? Or the state that the Editor receives from the frontend? Or something else? Just as a note, frontend changes will be prepared, and merged to staging just after this migration is run on staging.
Also, what do you mean by "send us"? Do you want me to post it here as a comment or?

[LarsTheGlidingSquirrel]

The content column of a random entity_revision row?

This is what I had in mind. I don't understand how migrations work very well so I can't really check the code. But I can definitely check if the resulting state looks fine.

Do you want me to post it here as a comment or?

No preference. Any way you see fit ☺️