PURPOSE
This commit removes the mass_mailing.campaign model. Instead of having a fully
fledged model, we will simply inherit utm.campaign. We will also add relevant
statistics on utm campaign model in order to use it in various applications.
SPECIFICATIONS
This commit adds leads/generated statistics in the kanban and
the form view of the utm campaign.
Kanban and form views will now display the number of leads and
opportunities generated with the campaign
TaskID: 2002029
PR: #34452
qmo-odoo
f49d83f07d