Add dedicatd SCL file for LNodeType Templates

[clepski]

User Story

As a user I wanted to store my LNodeType Templates in a dedicated SCL file so I can import them in other projects.

Acceptance criteria

• Make sure a LNodeType Templates file with the UUID "fc55c46d-c109-4ccd-bf66-9f1d0e135689" (edit by Nora: this is the correct UUID) exists

Frontend solution

Compare to the FE solution com-pas/compas-open-scd#381

Solution

• Add a database migration script which creates a SCL with provided starter content and the specified UUID
• It only runs if the migration has not started before

[clepski]

@JakobVogelsang Can you provide a base SCL file for LNodeType library?

[JakobVogelsang]

LNodeTypeBasic.ssd.zip