Add new prop getters to QuizEntity

[rgoessl]

Closes: https://desire2learn.atlassian.net/browse/BORG-4037

[github-actions[bot]]

PR Checklist:

Did you use a semver keyword in a commit message?

• [x] Yes I used one in at least one of my commits
• [ ] No but I will use a semver keyword in the commit message when I merge and squash

Did you paste the Jira ticket URL in the description?

• [x] Yes
• [ ] No as there's no corresponding Jira ticket

[d2l-github-release-tokens[bot]]

:tada: This PR is included in version 3.12.0 :tada:

The release is available on:

• GitHub release
• npm package (@latest dist-tag)

Your semantic-release bot :package::rocket: