Before this commit, discuss widgets had to wait for the route `mail/init_messaging`. This behaviour slowed down the loading of the web client. This commit solves the issue by rendering discuss widgets even when `mail/init_messaging` hasn't been resolved. For instance, the messaging menu displays a spinner until messaging becomes ready. Task-Id 2072835 closes odoo/odoo#37031 Signed-off-by: Alexandre Kühn (aku) <aku@odoo.com>