[FIX] web: do not open datepicker on focus

Before this rev., the datepicker was opened when a date(time) field
was focused (e.g. with keyboard navigation). We don't want this
behavior anymore, and we want the datepicker to open only when the
user clicks in the input. This rev. makes this change.

Moreover, this allowed to refined the keyboard navigation (ESC) in
editable list views: when a datepicker is opened, and the user
presses ESC, we close the datepicker, but we keep the row in
edition, whereas before this rev., the row was switched to readonly.

closes odoo/odoo#32408

Signed-off-by: Martin Geubelle (mge) <mge@openerp.com>