Add a nb_views indicator for maps

[virgile-dev]

Is your feature request related to a problem? Please describe.
Showing the nb of views (displays) a map gets is a good info for map editors that pubish public maps.

Describe the solution you'd like

• Log the nb of views for each map
• display the count on the user panel, somewhere on the map view and on the map card
• having a checkbox to opt out from views count ?

Describe alternatives you've considered
I'm using Matomo for this right now.
So it's a bit of knowing the tool and knowing it exist to get that info.