Allow positioning of IEDs

[ca-d]

We should add the IED positioning feature from @openenergytools/scl-editor to this, because two instances of the SLD designer don't play well with one another.

[danyill]

Currently the IED positioning uses an extension namespace within the IED element which is not well respected by the ICTs.

• Siemens DIGSI 5 or IEC 61850 Configurator removes the namespaced information.
• It causes difficulty opening files in GE Enervista UR setup because it removes the namespace.

I believe it will work much better with Siemens equipment if it is within a <Private> element and probably won't be scrubbed during a round-trip.

[danyill]

As part of implementing this feature, it would be helpful that when moving a container (bay, voltage level) the IEDs that are enclosed also move.

See https://github.com/OpenEnergyTools/scl-communication-editor/issues/28

[danyill]

Finally, it would be helpful if rather than an entire status bar with each IED as we currently have in the OpenEnergyTools designer prototype (shown below) we had a single item which when clicked displays a menu of IED names perhaps with manufacturer and type in brackets and ideally a search field for larger substations.

The IED button should only be visible once there is a substation element created, unlike the present prototype:

Additionally, most likely on removal of a substation element or a containing element, the coordinates of the IEDs should be deleted.

[danyill]

I'd like to have a go at doing some of these things as some of the above are a blocking issue for the use of the communication-editor.