This commit adds a `sequence` field in `event.track.location`, allowing event
managers to organize their event location as they want in the "Agenda" page.
To allow re-arrangement of the locations a bit more visible and easy, this
commit adds handle widget on track locations tree view, and removes the debug
group from the menu "Events > Configuration > Track Locations".
To match the order on agenda page and on the back-end, the same ordering
is applied at model level as well.
taskID-2942634
closesodoo/odoo#97763
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>