FEATURE: Configure the nodeIdentifier of the storage node instead of site and nodePath

[daniellienert]

In our use cases, the storage node can be identified by the node identifier.

To use this identifier in the importer has the advantages:

• The identifier can be found in the backend inspector - no need to look at the database
• The identifier remains the same, when the node is moved
• SiteNodePath and storageNodePath can be derived from the node identifier