Before this commit, when a popup was created and the user wanted to have
this popup on all the pages of his site, the popup was moved to the
footer. Unfortunately, this caused a lot of problems:
1) We had to disable the effects on the footer when the popup opened, so
that the popup would not block the page when the footer had a slideout
effect (see original commit).
2) The popup shared on all pages was attached to a footer template so
that if after setting the popup, the user changed the footer template,
he lost his popup.
3) Putting the popup in the footer led to an important limitation which
is that it was impossible to have a popup shared on all pages on a page
where the footer is voluntarily hidden (via the page visibility option).
This commit fixes all these problems by adding a shared section
dedicated to the shared popup on all pages.
Related to opw-2971181
X-original-commit: 0f131160097deb0693d7bdb4adc43fd69ea49c09
Part-of: odoo/odoo#107387
Guillaume (gdi)
6007264afb