Allign with Leave Request Period

This is equivalent to work done for Leave Request, at:
185285c4
(merge_request 493)

Follow a simple / non-simple approach, like for Task and its lines.

In default case, user would need only one Presence Request Period, which can be edited directly on PresenceRequest_view. So, in this case, hide the Listbox containing the Presence Request Periods and have default_presence_request_period being created / edited on background, which will acquire quantity, resource, start_date and stop_date from what is set at the view of the Parent.
In case one or more Presence Request Period are added manually, user would get listbox with sub-objects, and editing should be done directly on them, i.e. fields like my_default_presence_request_period_start_date will be disabled fromPresenceRequest_view.
Additionally, now Presence Request has it's own:
start_date: equal to the minimum start_date of all Presence Request Periods
stop_date: equal to the maximum stop_date of all Presence Request Periods
These values are set by interaction on Presence Request Period, triggered on setStartDate, _setStopDate. This helps so that presence_request_module listbox can have sortable dates.
Commit contains also test that should make it easier to understand.

[erp5_core] Remove quantity input field from category view form. Do not input quantity on category and use quantity unit conversion module instead.

[erp5_configurator_standard_categories] Use quantity unit conversion module to define quantity of category and stop using quantity property on categories.

To take into account organisations with multiple establishments and module containing DSNs for other organisations

Only quantity should be set

Proof is indeed it already changed

And update the related view

/reviewed-on nexedi/erp5!544

This reverts commit e1fa7611.
The fix was already provided by c1b8fa1a

Firefox doesn't display new line with: white-space: normal

replication test