Introduce Selection menu

[kieferrm]

In orde to improve discoverability of available editor functionality we introduce a top level "Selection" menu.

• Identify which commands should be in the menu
• How do we measure the success of the menu
• Implementation

[chrmarti]

One proposal is:

• Add Cursor Above
• Add Cursor Below
• Add Selection to next match
• Add Selection to previous match
• -separator-
• Copy Line Up
• Copy Line Down
• Move Line Up
• Move Line Down
• -separator-
• Expand Selection
• Shrink Selection
• -separator-
• Emmet: Expand Abbreviation
• Emmet… (opens command palette focusd on Emmet:)
• Issue: Exposing 'Rectangular Selection' ALT+SHIFT+ DRAG

[chrmarti]

Pushed without addressing the rectangular selection issue.

[chrmarti]

Feedback in #16253