Use model attributes instead of schema in CRUD generator

[WinterSilence]

Q	A
Is bugfix?	yes
New feature?	no
Breaks BC?	no
Tests pass?	yes
Fixed issues

[machour]

@samdark shouldn't we have tests in this extension, including & comparing outputs ? That would make it easier to track changes

[samdark]

@machour yeah but we don't have any :)

[rob006]

yeah but we don't have any :)

Maybe we should start with adding these, and only then start refactoring this extension. Right now reviewing such PRs is a nightmare - it is often really hard to understand what are the actual implications of some changes.