Added error handling for empty delegation input.

[lovoll]

If post endpoint for adding right keys is called with an empty list then return this as an error situation

Related Issue(s)

• POST/resources/rights gir 201 created selv om action lista er tomt og GET returer tomt lista på det #2436

Verification

• Your code builds clean without any errors or warnings
• Manual testing done (required)
• Relevant automated test added (if you find this hard, leave it and we'll help out)
• All tests run green

Documentation

• User documentation is updated with a separate linked PR in altinn-studio-docs. (if applicable)

[sonarqubecloud]

Quality Gate passed for 'Authorization Altinn.Authorization.Api.Contracts'

Issues
0 New issues
0 Accepted issues

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

See analysis details on SonarQube Cloud

[sonarqubecloud]

Quality Gate passed for 'Authorization Altinn.AccessManagement'

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
25.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud