DLSV2-538 Add clear button for competency questions

[daniel-manta-hee]

This pull request is intended to fix a bug reported in Jira ticket comment. There was a previous PR for developing this functionality and it's already merged.

JIRA link

https://hee-dls.atlassian.net/browse/DLSV2-538

Description

Made changes for inserting null result value on table SelfAssessmentResults when user clears previous assessment question result.

More details

Since queries already handle null results to cover a scenario where no result was yet provided, this would have less impact than inserting zeroes (e.g. sql AVG() ignores null values). After performing a left join, result would be null in both cases (no result ever provided or null result was inserted). Main difference between no result and a null result, is that result id is still a number if we have inserted a null result. Tried to find a scenario where this could be an issue among all these queries. But they seem to look for max ID which returns null Result in both cases (either no matches in SelfAssessmentResults or a match with null Result).

Screenshots

https://localhost:44363/LearningPortal/SelfAssessment/1/23

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Developer checks

• Checked null result is saved and retrieved correctly when user is completing selfassessments at the Learning Portal.
• Checked Export functionality handles null result and this overrides previous results.