fix: styling issue with SubEquipment editor

[JakobVogelsang]

Closes #1129

Two things that have been fixed

1. by mistake, the container for sub-equipment-editors was declared min size 64px. That is why it looked too strange. This declaration is only necessary for icon type components. SubEquipment is never rendered as icon.
2. sub-equipment-editor do not need to be within a container. That is only necessary when grid type display is used. E.g. Bay within VoltageLevel or ConductingEquipment as icon within Bay. In all other cases, just adding it as child editor is enough. action-pane will do all the styling.

There is no regression test as I only touched CSS. Just updated snapshots due to the changes html

[danyill]

LGTM