IDE-297 Catrobat Language Test (CLT) for the "Set background ___" brick

[Kale2605]

https://catrobat.atlassian.net/browse/IDE-297?atlOrigin=eyJpIjoiM2Y0ZGZjOGY3MGJiNGYzZDllZGJlYjRkZmI3MGQ1YjgiLCJwIjoiaiJ9

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[dorianpercic]

Rebased the PR.

[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

See analysis details on SonarQube Cloud