Improve how course navigation works for users after re-accesing a course

This is a recurrent issue affecting BMA clients and the community.

The main problem right now is that the user after leaving and accessing again to a course is always "enclosed" in the section where the last visited activity is placed. This creates some issues in courses that are designed to display always the full list of sections.

A possible solution is to remember the navigation state:

• if the user accessed an activity from the main course page with all the sections displayed, they should see all the sections displayed when they return to the course
• if the user accessed an activity from inside a particular section, they should see only that section when they return to the course

We need to discuss also if the previous should apply only if the course format is configured to "Show all sections on one page" and avoid doing it if the course format is configured to "Show one section per page" as the latest configuration is more consistent with what we do now.

At the same time, if we are displaying all the sections, we should discuss if we should allow them to be collapsed (this is a new feature introduced in 4.2)

This needs proper discussion