Properly define relational fields as owner/owning/content.
For instance, with viewing attachment in a dialog, the modelling
looked roughly like this before the commit:
```
attachment_viewer -----> dialog
```
- where attachment viewer owns dialog
This commit changes it to:
```
attachment (image/card) ------> dialog -------> attachment_viewer
```
- where attachment (image/card) owns the dialog, and dialog has
attachment viewer as content
These changes should make modelling of dialog feels more natural.
Task-2738648
closesodoo/odoo#83519
Signed-off-by: Sébastien Theys (seb) <seb@odoo.com>
Alexandre Kühn
48700416c1