Feature request: improvements to Entity References window.

[JeffreySax]

The Entity References window is a great resource. Here are a few things that could improve it:

• Point out its location (View > Other windows > ...) in the documentation.
• Hitting enter for a search should put the focus on the list of results (if there are any).
• Double-click on an item should copy it.
• In the dark theme, the contrast between the selected item and other items is minimal.
• The "Insert as" panel should be moved to the toolbar. For code entity lookups, it is natural to have a wide window, but much vertical space is taken up by this panel.