[REF] website_slides: rework standard lesson page view

Purpose of this commit is to perform a cleaning and upgrade of the lesson
view in front-end when not using the fullscreen mode. This page had not
been updated since eLearning addition.

A method is added on slide model to have a protected method computing quiz
related information on a given set of slides, notably potential karma gain,
gained karma and number of attempts. It is mainly a code move from controllers
now working in batch.

Some linting is also done, notably a badly-named file.

See original eLearning task for main specifications [1].

Commit linked to task ID 1941250 and PR #31657.

[1] See task ID 1902304

Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>