Rename `upload_*_to_s3` to no longer reference s3

TNL-534
Add coverage for cohort view's `showSection` link

TNL-550
Some strings were missing i18n calls
Replace course status message
Introduce new switch for paver run_quality command.

When using -p, the underlying diff-quality command will pass that
number as a value for --fail-under.

For example,
  paver run_quality -p 75

Will pass 75 into the --fail-under switch on diff-quality.

Also upgrades diff-cover in order to take advantage of this funcitonality.
Merge pull request #5534 from edx/i18n-cms-index

Some strings were missing i18n calls
Verify cohort strings are scraped for translation
Create standard way of updating a task's progress

TNL-566
Bump the report downloads poll interval to 20 seconds

TNL-565
Merge pull request #5582 from edx/dan-f/cohorts-internationalization

Ensure all user-facing cohort-related strings are internationalized
Merge pull request #5528 from edx/dan-f/data-download-tech-debt

Student profile CSV background task tech debt
Merge pull request #5552 from edx/benp/diff-cover-threshold2

Benp/diff cover threshold2
edX Solutions Team: Open edX Server API contribution