"Resolve discussion via new issue" should include quotes of all unresolved comments

For this feature, when you choose to resolve a discussion via issue, it quotes only the first message in the discussion, with a link to the full discussion and the number of additional comments.

I think it would be more useful if we quoted all unresolved comments in the discussion. These notes often add additional context or contain the actual thing that needs to be addressed. Loading the entire MR just to view the whole discussion can be slow and adds an additional step.

cc @DouweM @jramsay (please correct these if I have the wrong people. New categories, rabble rabble.)