The prevoius implementation was only taking into account the last inventory
specific to the location.
This change includes also inventories done on parents location.
Also display the computed last inventory date in the form view.
Several changes were done because of the code review:
* The category of the module is now "Warehouse", in alignment
with the categories user in OCA (https://odoo-community.org/shop)
* The list of fields in the depends() for the method
_compute_last_inventory_date() missed several fields, that are
now listed as dependencies.
* A new unit test has been added to account for the concern of the
functional needing a compute_sudo in its definition, just in case
a non privileged stock user was stuck into permission problems.
This new module adds a stored computed field on locations that stores
the last inventory date for the location, for validated inventories.
This is only computed for leaf locations, not parent ones.
