Changed the way the header selector behave when the selection changes.
Before this commit, the header selector was only checked when clicked and
was unchecked as soon as any other record was unchecked.
Now, the header selector reflects the current visible selection:
if all of the other visible selectors are checked, it will be checked.
Folded records are not considered visible, thus only records from active groups
and from the current pager will be taken into account.
closesodoo/odoo#36522
Signed-off-by: VincentSchippefilt <VincentSchippefilt@users.noreply.github.com>