[MERGE][REF] website_slides: make eLearning an application with its own backend

PURPOSE

eLearning should have its own application in manager. Indeed this is becoming
a big application and having it embedded inside Website application is not
enough anymore. It should also hold updated and easy-to-use menus,
navigation, actions and views in backend.

SPECIFICATIONS

Update manifest and make website_slides an application separated from
website embedded menus.

Implement new menu structure

* Courses
* Courses
List view: Course Name, # Views, # Attendees, # Ratings, Revenues,
Reviews
* Contents
* Reviews: kanban view of channel reviews
* Certifications: kanban view of surveys of type certificate

* Forum
* Forums: add columns to list view: Posts (questions count), Views
(sum of views of each post), Answers (sum of child_count on each post),
Favorites (sum of favourite_count on each post)
* Posts: add columns to list view: Views / Answers / Favourites

* Reporting
* Courses: list view on slide.channel model, ordered by # views.
List view: Course Name, # Views, # Attendees, # Ratings, Revenues;
* Contents: graph view on slide.slide model
Area Graph: X month
Y measure: # Views (others measures: Attendees, ...)
Group by: course (color)
* Revenues: graph view on sale.report model showing revenues of eLearning
courses.
Area chart, X: monthn Y: €, Color: course
* Certifications: list view on surveys of type certificate
Columns: Title, Survey Stage, Registered People, Certified People, Attempts
Success Rate (certified/attempts), Average Results
* Reviews: see kanban of latest reviews;
* Quiz: list view on slide.question model.
List view: Add # Quizz Trials, # Quizz Passed, Avg Attempts
* Forum: graph view on forum.post model
Area chart: # Posts created by months, color=forum

* Configuration
* Settings
* Allow Forum on Courses (installs website_slides_forum)
* Allow Certifications (installs website_slides_survey)
* Allow Selling Courses (installs website_sale_slides)
* Course Tags
* See channel.tags.group with label Course Tags, form view allow to
configure group tags
* https://drive.google.com/a/odoo.com/file/d/1G0g2UnG5cZG55EXQ5icbgwe7T2eSZskT/view?usp=drivesdk
* On click: open :https://drive.google.com/a/odoo.com/file/d/1I_PW3aZAbrslXadiYqmVF-_6dGXx8knd/view?usp=drivesdk
* Content Tags

Add course (slide.channel) kanban view. Each tile should contain

* Title of the course
* Tags below the title
* Primary button "New Lesson"
* Statistics :
* Attendees
* Running (progress != 100%)
* (if one content is certificate) Certified or Finished
* See : https://drive.google.com/a/odoo.com/file/d/13K8FmkbwmBG4JQ5gH3Q5T8OlWPs3blcu/view?usp=drivesdk
* With FP remarks https://drive.google.com/a/odoo.com/file/d/1mb7LUT0VUNs5fMcKB9c0Bfaqk2-XFFuu/view?usp=drivesdk
* Add "Sales       150.00$" below "Watch Time" if type "on payment". Same
info than the smart/stat button on the course itself. Click on the amount
sends to Reporting Revenues (same than on the stat btn)

Add review (rating.rating) kanban view. Each tile should contain

* Kanban view, full width, no default group by
* Order by date (most recent on top)
* See: https://drive.google.com/a/odoo.com/file/d/1IYE1QBIJa26BLugRiafyBop-srkYwndC/view?usp=drivesdk
* add a tag for unpublished comments
* Add the pic of the user above the stars
* Click on card, send to front-end and able to (un)publish the comment
* Kind of what's on the front-end:  https://drive.g



Improve course form view: add a revenue stat button displaying the total
of sale order linked to the course's product.

Integrate a button on slide.channel form view allowing to perform a mass
mailing on course attendees. Do a flow similar to event.

Remove "Our Documentation" dummy default existing data. It makes no sense
to have void data. Instead just add a small explanation text in eLearning
front-end telling the user to create its first course if he has rights to
do so.

In order to better show the new backend add some demo data for missing
numbers, notably

* sales: add confirmed sale orders in order to have revenues value;
* forum: add some posts and answers;
* quiz: update slide.slide.partner demo data to hold quiz attempts count

LINKS

Task 1978729
PR #35061

Co-Authored-By: Thibault Delavallée <tde@odoo.com>
Co-Authored-By: Jérémy Hennecart <jeh@odoo.com>

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