search: add mutation to trigger actions immediately

Created by: stefanhengl

Feedback from the first testers of code monitoring was that it would be great if there was the possibility to trigger actions immediately and not to wait for a commit to happen. This PR adds a mutation that allows just that. For now, the mutation is restricted to site admins. The plan is to add a button to the UI behind a sub-feature flag to allow site admins to troubleshoot or test the configuration.