Redirect to enroll page when not enrolled

What does this mr do?

When a user tries to access a lab page when they are not enrolled to the edition of the course, they will be redirected to the enrol page.

Screenshots

before

after

Does this MR meet the acceptance criteria?

• I have added a changelog entry to reflect the significant changes I made.
• Tests were created to test the feature.
• I have updated the documentation accordingly.
• I adhere to the style guide. Closes #381 (closed)