[4.2] Clean up relationship directory - move partials to inc subdirectory & rename relationship_select and repeatable_relation

[tabacitu]

WHY

BEFORE - What was wrong? What was happening before this PR?

Inside the relationship directory we had a bunch of stuff all in one place. Both subfields and partials.

AFTER - What is happening after this PR?

The partials are all moved to a relationship.inc subdirectory, so all that's left in relationship is the subfields.

HOW

How did you achieve that, in technical terms?

• Moved files to inc and added inc where they are referenced.
• Put the code inside field_attributes into fetch_or_create since it was only used there.
• Renamed relationship_select to select
• Renamed repeatable_relation to entries

Is it a breaking change or non-breaking change?

Semi-breaking. Because one of the changes is inside the InlineCreateOperation. Though I doubt anybody has ever overriden that method.

How can we test the before & after?

No need to test, it was a few simple find&replace commands. But if you want, the Monsters CRUD (Create/Update) should work the same after this PR. No functionality was added or changed, just the directory structure changed from this:

To this:

[tabacitu]

@pxpm I want to merge this TODAY, after our meeting. No point in postponing this, the more we do that the more chances of breaking changes when we do. In any case, I think git is smart enough to know these are the same files, just renamed - it seems so from the github diff. So I don't think they'll pose any problems.

But I'm going to wait until we talk today, to be sure you've submitted all changes to these files already.

[tabacitu]

FYI - Github couldn't do the merge automatically, but my local Git could - I got absolutely no merge conflicts. So maybe we shouldn't be so scared of these file-renaming changes in the future 😉