This commit adds the background per section feature.
If the section to display has a background image configured, the background
will be refreshed using that section background image.
If the section has no background, the survey background is used.
The background is refreshed at the same time that the next question is loaded.
To ease technical maintenance and to keep it simple, the background is always
faded out/in at each page change only if there are some sections on the
survey that has a specific background image. If no background image are set on
the survey sections, the background will never be faded out.
Note: The next section to display depends on free text (section with
description) configuration and on conditional questions.
The next section to display can be the next question's section or directly
the next question itself (if the question is a section).
This section's background image implementation works both for the regular
survey form as well as the "live session" mode of the survey module.
Task-2225393
closesodoo/odoo#79156
Signed-off-by: Warnon Aurélien (awa) <awa@odoo.com>
David Beguin
fd75481d52