Description

This PR adds a new panel Learning to PSAT.

• Wiki, stories and two new panels help center, dev site are put as children to Learning section.

Relevant Technical Choices

Testing Instructions

• Open the PSAT panel and you should Learning the sidebar item.
• Click on it, it should open small tiles, containing four items.
• Redirects should work from the tiles.
• Help center and dev site when opened, by mouse, key down or internal navigation, it should open a url in same tab.

Additional Information:

Screenshot/Screencast

Checklist

• I have thoroughly tested this code to the best of my abilities.
• I have reviewed the code myself before requesting a review.
• This code is covered by unit tests to verify that it works as intended.
• The QA of this PR is done by a member of the QA team (to be checked by QA).

Fixes #