Add field for related references / identifiers

Currently, the SMS does not support to add any related references / identifiers. But it would be important to have a specific (or even multiple) fields, were we can refer to publications, datasets, other resources, etc.

Please note: In this issue, we do NOT mean to describe relationships between devices / platforms / configurations or different versions of these systems, but rather to refer to an external resource like a dataset or a publication.

In particular, we can think of two concrete use-cases:

• A collection of sensors / platforms / configurations has been used for a scientific publication and I want to add the DOI of that paper to my SMS
• I have published some data from a configuration in a repository and now want to add the identifier to the SMS

Similar to the discussions on "internal" or technical relationships, we could also use the relationTypes from DataCite for that (https://support.datacite.org/docs/connecting-to-works).

We can think of two different implementations for that

• Two new fields in the Basic Data form with a Dropdown-menu for selecting the relationType and a field for the respective identifier. This should be extendable so that we can add multiple identifiers and relation types
• A new tab in the Configuration, where we could also manage even more complex "internal" relationships (e.g., between Devices, etc.)