[FIX] ir_model: cascade delete custom o2m and related fields

Before this revision:

* Install a module, for this example we'll use `project`
* Create a o2m field or a related field whose inverse is a field from
the `project` module.
* Uninstall the `project` module.

Result -> BOOM! The registry can't be reloaded because it can't find the
inverse field of our custom field, ayayay!!

After this revision, this shouldn't break the registry anymore because
we create two m2o fields which will trigger cascade deletes for both o2m
and related fields upon the deletion of the inverse field, these fields
are both computed stored fields and they're not shown to the end user,
this is all done "under the rug".

Task-ID: 58808

0 files changed, 0 insertions, 0 deletions