[User Feedback] Render evidence inside the Feedback Details section, so people can see if a message was automatically tagged as spam or not

[ryan953]

If you look at a feedback in the issues page (like https://sentry-test.sentry.io/issues/5345429096/?project=4506072436572160&referrer=issue-list&statsPeriod=14d) then there's an Evidence section rendered:

We should show the is_spam field on the feedback details page, so people can know how we classified things. For example it could say classification: spam or classification: feedback and link to docs, depending on the evidence value.