enhancement: add omitempty to optional fileconfig fields

[avirtopeanu-ionos]

If someone imports fileconfiguration and wants to generate a sample config file, the generated file will include empty optional fields

        - name: region-less-API
          endpoints:
            - location: ""                  <-----------
              name: https://api.ionos.com/region-less-API/v1
              skipTlsVerify: false

and this is weird as we expect certain APIs to not have locations.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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