[IMP] web: trigger fast owl re-render from python

Because why not?

We often need to re-render the user interface from python, but limited to call a browser reload (redirect to current URL).
With this simple client action tag `soft_reload` - we can quickly reload the UI, without a hard refresh.

An example use case: refresh the kanban when an onboarding step is done via a dialog. See `validate` in 'account.setup.bank.manual.config'

closes odoo/odoo#133643

Signed-off-by: Francois Georis (fge) <fge@odoo.com>