sonarcloud on external PR's

[Apfelwurm]

becuase of github security concept the sonarcloud scanning does not work with external pull requests and thats okay, because the tests are running code which is provided by the pr and could expose secrets.

we have to do one of those 3 things:

• implement https://github.com/imjohnbo/ok-to-test so a comment with /ok-to-test sha= is required to run the testing
• use the pull_request_target with type labled to run the test and lable each external pr with a lable
• skip the sonarcloud test if no login is available which would disable the sonarcloud scan for external PRs, which is not good.