[IMP] web: reload currencies when activating one

Active currencies are given in session_info, in the page source.
When the user activated a new currency, he had to reload the page
to make the browser aware of that new currency (without reloading,
there was no currency symbol displayed next to the amounts).

This rev. forces a reload of the currencies each time a currency is
edited.

Task #1838654

closes odoo/odoo#31192