Limit highlighting on drag over open editors by checking if dragged item can be dropped

* Add "Click to view details" on extension list items' aria-labels

* Reword message

Fixes #52073

Add setting for highlightActiveIndentGuide #49148

Mention the mouse middle button drag to rectangle select feature in the Interactive Playground

Fix for issue #39458

also add negative context key for simplicity

path labels: if resource belongs to a root to show relative label use paths not toString (it encodes)

fixes #52512