As some formatting tools already exists, it is time for float_time
conversion to have its own. Purpose is to extract formatting logic
from the float_time qweb widget to tools, in order to reuse it
in mail.template (jinja).
We named it 'format_duration', to follow babel convention. This
can bring confusion with the duration qweb widget, but this widget
should be called 'timedelta', as it is more generic than this one.
Task-2025396
closesodoo/odoo#34417
Signed-off-by: Jérome Maes (jem) <jem@openerp.com>