Comment Details: show Delete Permanently only for Trashed comments

[ScoutHarris]

Ref: #17087 , #17200, #17297

From discussion with @mattmiklic , this enables the Delete Permanently button only for Trashed comments. When trashing a Spam comment, the comment is now marked as Trash instead of deleted.

To test:

• Enable the newCommentDetail feature.
• Go to My Site > Comments.
• Select a Spam comment.
  • Verify Delete Permanently does not appear.
  • Verify selecting Trash moves the comment to the Trashed filter.
• Select a Trash comment.
  • Verify Delete Permanently does appear.
  • Verify tapping Delete Permanently deletes the comment.

Regression Notes

1. Potential unintended areas of impact
   N/A. Feature incomplete.

2. What I did to test those areas of impact (or what existing automated tests I relied on)
   N/A. Feature incomplete.

3. What automated tests I added (or what prevented me from doing so)
   N/A. Feature incomplete.

PR submission checklist:

• I have completed the Regression Notes.
• I have considered adding unit tests for my changes.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[peril-wordpress-mobile]

You can trigger an installable build for these changes by visiting CircleCI here.

[ScoutHarris]

Hey @dvdchr . With this change, I should be able to DRY the moderation methods in CommentDetailViewController a bit. I'll do that in a follow-up PR.

[peril-wordpress-mobile]

You can trigger optional UI/connected tests for these changes by visiting CircleCI here.

[dvdchr]

LGTM!