fix(matomo): #37547, Opt-out banner improvements
fix(matomo): #37547, Opt-out banner improvements

The opt-out banner link scrolls to the privacy statement, at bottom of the profile section.

Preferences are saved under '/userbook/preference/tracking'

entcore/infra-front,entcore/js-infra,entcore/infra-front,entcore/infra-front,entcore/js-infra,entcore/infra-front