- changed message and added i18n

The changes in 5152 appear to have introduced a
 performance problem on stage, so we're going to
 revert them for now.

- Update key comparisons for Opaque Keys
- Search for 'problem_check' instead of 'save_problem_check' when
  filtering TrackingLogs.

Calling the client root was causing the module store to be modified,
affecting test in other Django applications that rely on the default
state of the module store.

Some tests test were using `CourseFactory` buy not deriving from
`ModuleStoreTestCase`, introducing a course leaks that broke other
unrelated tests.

For microsites, since we don't have a footer override yet for django templates, remove the footer all together

Disable sending activation email also when doing external_auth and setting BYPASS_ACTIVATION_EMAIL_FOR_EXTAUTH=True

This reverts commit 3f159ea5.

TNL-153

LMS-11380

TNL-392

TNL-284

fix the translation issues

added a check if a user is already registered in a course. Changed the messages

added course depth=0 and removed pep8 violations

only redirect to dashboard if user has course enrollments, otherwise remain on the course catalog page (aka homepage or root)

update lettuce test to match new expected behavior

add Jason's feedback

only apply new redirect logic for microsites

switch to use a feature flag to determine whether to support redirect behavior

To include size warning of 10 MB.  Also updated styling on existing learn more
links

but just use old to get query info.
LMS-11396

as well as draft
LMS-11395

leak out to callers.
Also, use the return from update_item rather than assume
it was just side effecting.
LMS-11361