feat(Export): Include Question Used column in Peer Chat export

[geoffreykwan]

Changes

• If "Student can select questions to use in Peer Chat" is enabled, include "Question Used" column in the export
• Now only show either "Prompt" or "Dynamic Prompt" column, not both. Previously we would show both.

Test

• If "Student can select questions to use in Peer Chat" is enabled, show the "Question Used" column
• If a student used a question for their response, make sure it shows the question they used in the "Question Used" column
• If dynamic prompt is enabled, make sure the "Dynamic Prompt" column shows up and the "Prompt" column does not
• If dynamic prompt is not enabled, make sure the "Prompt" column shows up and the "Dynamic Prompt" column does not

Closes #1482

[breity]

Functionality looks good.

There is some duplication added. One way you could simplify might be to combine each of insert column functions that are very similar into two functions, insertPromptColumns and insertQuestionColumns. So, for example, the logic for each of the 4 separate insert prompt column functions would just go in one (insertPrompColumns). What do you think?

[breity]

Changes look good.