[#12588] Improve test code coverage of QuestionResponsePanelComponent

[leyguan]

Part of #12588

Outline of Solution

I added a few tests to cover the uncovered code.
I tried to cover everything. It's ready for review.
I only fix the test for one component, so I use the description "Part of #12588".

[leyguan]

It seems I mistakenly add an unexpected file lint-output I used to test locally. How should I fix this?

[Andy-W-Developer]

Make a copy of the entire folder first just in case.

Then give this command a try:
git rm --cached

Commit and push like a regular commit.

[leyguan]

I have removed the unnecessary file and it's ready for review.

[cedricongjh]

test cases LGTM, could I trouble you to add the method that is being tested in the test string e.g. it('canUserSeeResponse: should allow instructors to see responses when intent is INSTRUCTOR_RESULT'), this is something we are doing for newly added test cases as it makes it easier for future developers to see exactly which method is being tested

[leyguan]

I only added tested methods for the newly created tests. Or do I need to add for all of them?

[cedricongjh]

LGTM, thank you for your contribution!