[WJ-1032] Add file_rollback

[emmiegit]

This adds rollback capability to files, which like for page rollbacks, changes a file to have the same state it had earlier. (This cannot be used to move a file to a different page). While working on this, I discovered a bug in file moves where it wasn't properly updating the name.

Example output after local tests:

 revision_id | revision_type |          created_at           | revision_number | file_id | page_id | site_id | user_i>
-------------+---------------+-------------------------------+-----------------+---------+---------+---------+------->
           1 | create        | 2024-10-10 08:52:01.028316+00 |               0 |       1 |       1 |       1 |       >
           2 | regular       | 2024-10-10 08:52:13.901203+00 |               1 |       1 |       1 |       1 |       >
           3 | rollback      | 2024-10-10 08:52:21.541878+00 |               2 |       1 |       1 |       1 |       >
(3 rows)

[Zokhoi]

What does PageRevisionType::Undo mean? Is it like the opposite of a rollback?

[emmiegit]

Undos are a planned operation. I am avoiding the term "revert" because it means two different things in git vs wikidot, and instead have two unambiguous terms:

• Rollback (what wikidot calls "revert", what git calls "reset") is where you set the current state of a page or file to some revision in the past.
• Undo (what git calls "revert") is where it applies the opposite of the given revision. Since this involves applying a diff, it can fail.

An example of the difference between the two. Imagine we have a page with this history:

Revision 10

**Item #:** SCP-XX

**Object Class:** Euclid

**Special Containment Procedures:** SCP-XX is to be kept in a cardboard box.

Revision 11

**Item #:** SCP-XX

**Object Class:** HAHA EPIC TROLL

**Special Containment Procedures:** SCP-XX is to be kept in a cardboard box.

Revision 12

**Item #:** SCP-XX

**Object Class:** HAHA EPIC TROLL

**Special Containment Procedures:** SCP-XX is to be kept in a cardboard or paper box.

So here, revision 11 is vandalism and we'd like to remove it. But the page has been edited since, so that means we'd lose any subsequent (legitimate) changes with a simple rollback. But using undo, similar to git revert, we can remove just the specific change from 10 -> 11 and leave the 12 revision in-place.

So basically it would produce the 11..10 diff (not that this is the inverse of the 10..11 diff that was applied in revision 11):

3c3
< **Object Class:** HAHA EPIC TROLL
---
> **Object Class:** Euclid

And then we could attempt to apply it.

(If there are conflicts, then like git revert, we should error out rather than attempting to ram our way through. Also, we should have some way of allowing a user to verify that the undo change is what they want before doing it.)

[emmiegit]

thanks @Zokhoi