Show correct answer in "Result (per quiz element)"

I believe the first part of solution should be a discussion about the design of quiz_option.is_correct template variable, which is defined at https://git.drupalcode.org/project/webform_quiz_elements/-/blob/1.0.x/sr.... It's currently true only if the option is also selected. I'm going to patch this, so this can be implemented at least on the template level.

MR contains is_correct modification, as mentioned above.

Remaining work:

• this should be probably checked from the UX point of view, since it changes meaning of the messages-status class styling
• this should be made configurable, as mentioned in the FR description

I find the option to make the correct answer display configurable quite interesting. However, a simpler alternative might be to use the feedback field, as shown in the documentation example. This approach would allow:

1. Explaining why the answer is incorrect
2. Indicating what the correct option would be