Show all changes and comments in one place

**Is your feature request related to a problem? Please describe.**
It is difficult to simply review comments on a pull request. If I left a comment, and I want to know if someone has replied or resolved the comment, I need to open the file and scroll to the comment. This is annoying.

**Describe the solution you'd like**
On the Bitbucket website, when you open a pull request, you can see all of the comments for that pull request in a single page. It also shows a little code snippet, and allows you to load more lines in either direction if you need more context.

This is what I want in the extension. In the "Files Changed" section of the details page, it could have a toggle that expands all changes and shows all comments. Then you can scroll in place and respond to each comment.

Alternatively, each changed file row could be expandable to show the changes and comments, and at the top would be an option to expand all / collapse all / always expand all / etc. Ideally, it would have a way to set the default to expand all or collapse all.

When collapsed, it should still show if there are comments on the file, as it does now. But it should show if there are new comments or replies. Maybe show the number of comments and replies. And it should indicate if they were resolved. It should change the icon for this, not remove it, so you can see clearly that it was addressed and not missed.

**Describe alternatives you've considered**
Instead of placing this in the files changed section of details, this could be its own page as a sibling to details.

Start at the Files Changed section on the pull-request details page and trace how collapsed file rows currently expose comment indicators. Compare the existing behavior with the requested expanded view, comment and reply counts, resolution state, and expand/collapse preferences. Done means comments and code context can be reviewed and answered in one place without losing file-level status.

Written by the indexing model from the issue text.