This commit fixes a few issues with courses which have certification
* fix links to already passed certifications: currently it crashed, now it
redirects to the certification end screen;
* "Begin your certification now" green box link now has same behaviour
as links in the list view. It redirects to either the start certification
screen or the first slide in fullscreen mode. Moreover once the user has
started the course (at least one completed slide) this box disappears as
it is not really useful anymore;
Some dead code is removed.
Commit linked to task ID 1978530 (fixes linked to internal testing).
qmo-odoo
ef3ccce079