Before this commit, unread and needaction shown in messaging menu
was inconsistent with discuss sidebar.
In discuss sidebar, unread channel are bold, and needaction are
shown with badge + counter. In messaging menu, previews could be
either unread or needaction previews, and channels had 2 previews,
one for unread, and the other for needaction.
This commit make the messaging menu preview of channels more
consistent with discuss sidebar:
- channels have a single preview for unread and needaction
- unread messages make title bold, unread counter is no longer shown
- the counter displays needaction on this channel instead.
This commit also improves ordering of messaging menu items, so that:
- needactions have precedence over non-needactions
- unread channels have precedence over read channels
Task-3293723
closesodoo/odoo#120144
Signed-off-by: Sébastien Theys (seb) <seb@odoo.com>