[Improvement] Improve process of create/editing data links

As an outcome of our Community Meeting in March 2025, we reviewed the entire process of data linking in SMS. In Ticket #101 , some suggestions were made to improve the view of the created data links, and a preview has already been implemented. As a next step, the process of creating (and editing) new/existing data links should also be improved. We will use this ticket to collect information. The following points are already available in tickets:

- Highlight or sort already linked data streams (#100 )
- Using a counter when identical measured quantities are used multiple times (#96 )