Feature/improve comment context

[micahmo]

Pull Request Description

This PR is a small improvement to comment context. It's not quite the full implementation that we need to add (described here) but it helps a little. Currently, the selected comment is highlighted. However, if there is a long post, you may have to scroll down quite a bit before you can see the comment. This PR adds the ability to scroll to the first comment. Now it still may not show the highlighted comment immediately (if it's deep down in the thread) but at least it will put you in the right area. I also fixed an issue where using the navigation buttons would lose the comment context.

Note

Previously the "View all comments" button was built as part the 1st indexed widget in the list. As a result, scrolling to index 1 would go to the top of the button instead of the top of the comment. I moved the button into the 0th widget (i.e., the post body), which fixed the scroll issue, but it meant that the button couldn't participate in the SlideTransition, so I added a new animation for the button to disappear. It arguably looks a little better now. 😊

Review without whitespace.

Issue Being Fixed

Issue Number: N/A

Screenshots / Recordings

Before

qemu-system-x86_64_tD8npKLocQ.mp4

After

qemu-system-x86_64_oDSYCzc5Ua.mp4

Checklist

• Did you update CHANGELOG.md?
• Did you use localized strings where applicable?
• Did you add semanticLabels where applicable for accessibility?

[hjiangsu]

LGTM!