Don't pin the commit in the details view when I click on a diff

[firelizzard18]

The reason I asked #2585 is that the commit in the details view becomes pinned when I click on a file to show its diff. That feature makes "gitlens.rebaseEditor.showDetailsView": "selection" almost entirely useless to me. The interactive rebase is most useful when I need to clean up a long sequence of commits with bad commit messages. So I need to be able to click through diffs to figure out what a commit does. The pinning behavior makes the details view useless for that.