https://topcoder.atlassian.net/browse/PROD-2560 - Issue in checking and submitting the code

This PR:

• fix issue where tests errors and hints are flashing when you re-check code
• once a lesson is completed, keep the "completed" state even if the user changes code. This is according to latest FCC changes/behavior: https://github.com/freeCodeCamp/freeCodeCamp/blob/main/client/src/templates/Challenges/classic/lower-jaw.tsx#L104
• add a new state prop to keep track of running tests. This helps keeping the UI in sync and will help us add a loader to the "check code" buttons while the tests are running (right now I only added '...' as an indicator)