Emit "itemMiddleClicked" when Ctrl-clicking a view in single selection mode

When Ctrl can't cause a change in selection, so instead emit `itemMiddleClicked`.
This way one can Ctrl-click a Place or folder in Folders panel to open it in
a new tab, similar to what web browsers.
1 job for master in 7 minutes and 16 seconds (queued for 9 minutes and 5 seconds)
Status Job ID Name Coverage
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passed #86588
linux kf5-qt5 qt5.15

00:07:16

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