[IMP] base: improve res.country.state views
[IMP] base: improve res.country.state views

Allow to group by country
Add default search filters
Improved help message

closes odoo/odoo#29926

Signed-off-by: Martin Trigaux (mat) <cc7c5be316e48d137cbb549833b85d91034d799d@odoo.com>
ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo