Enhancement: Treat diff viewer tabs like IDEA's commit tool

[reitzig]

Based on using IDEA's new non-model commit tool, I expect a single (and double, actually) click in the review file tree to open the selected diff in the currently open diff tab, if any.

The current behaviour is that a single click does nothing, and a double-click opens a new tab.

[jBuchholz590]

I'd like to add on this: I usually use Ctrl + D (Show Diff) to open the diff viewer in a new window (so I can use my whole desktop to view changes). This is currently not possible forcing me to open a diff via double click and then dragging the opened Tab out of Intellij to convert it into a standalone window.

It would be splendid if there was a way to emulate this behaviour :)