Add new and user-defined data object to given LN class

[JakobVogelsang]

As a user of this plugin I would like to add a new data object to a given LN class. This is especially necessary with data objects that cannot explicitly defined in the NSD such as the GGIO.Ind where you can have GGIO.Ind1 and GGIO.Ind2 and so on.

Requirements:

• add a button Add user DO that opens a Add Data Object dialog (see Mock)
• The dialog should display a select field with supported CDC classes (see more information)
• The dialog should display a text input for the DO.name. This one should follow the pattern given in the Ed2.1 schema
• When add button is being clicked some steps must be followed:
  • call the function nsdToJson from and receive back the CdcChildren object
  • create a new object CdcDescription and add the CdcChildren, tagName = DataObject, descID = '', and presCond = O
  • attache newly create object to the treeUI.tree record of the type Record<string, CdcDescription> where the key is the name from the dialog
  • this should update the UI and the new data object with its structure should be visable
• update the insertSelectedLNodeType to the new API where
  • the currently passed lnClass is passed in the object logicalnode.class
  • in addition to that pass the tree object treeUI.tree through logocalnode.data

Mockup:

[Sander3003]

Bring this functionality back into the openscd organistaion including this story

[noraeb]

Button label and dialog title: Add Data Object

[Sander3003]

https://github.com/openscd/scl-template-update/issues/1