Layout blocks - Delete widget

As a Studio app builder, I can delete a widget when configuring a layout block

AC

• Delete button is available when hovering on the widget
• Pressing the delete button deletes the widget

• When I delete a widget containing other ones (e.g. a column), its content is also deleted

• Analytics event is sent when pressing copy
  • Category: Described according to NXS-5742
  • Event: Widget delete
  • Label: [Widget name]
  • Value: 0
    (goal: usage stats and understand work flow)
    (value: when done using UI = 0, keyboard = 1 => allows us to measure adoption for keyboard shortcuts)