Custom metadata can be:
- string/text/list/date (like existing)

Custom Metadata are inherited from parent folder.
=> if a parent has a custom metadata defined, it will be displayed as defaut input value in modal

Metadata can be applied for folder
=> they shoudl be inehrited from parent

If item is a folder there is an option to apply recursively the metadata

If metadata are not required the > More option is collapsed
If at least one metadata is required, the required metadata are visible, the optionnal metadata are still hidden by default
(to be checked with design)

Technically:
- POST/PUT docman_items existing routes should be updated and should enable the saving of new metadata
- GET docman_items should return the required
+ possible other values for list
+ type of metadata field