Selection focus and context menu in CollectionEditor

Description

There are three issues with the current context menu implementation.

1. When you select something in the CollectionEditor, the focus/selection is wrong.
Expected: Entire row is selected
Actual: The cell you clicked on is selected.

2. When a row is selected (after the point above is fixed), the context menu should be visible.
Expected: The context menu is visible to the far right.
Actual: it is only visible if that cell (to the farthest right) is selected.

3. The context menu should be openable via the keyboard.
Expected: When the row is selected (see point 1 above) and I press Enter, the context menu should be opened and selected so that I can make a selection there.
Actual: The context menu can not be opened via the keyboard, not even if that cell is selected.