Create service-user-mapping analyser

based on a discussion with joerghoh, i would like to suggest that we create a dedicated analyser for service-user-mappings.

This feature would include the following 2 checks:

• validity of service-user-mapping
• usage of deprecated service user mapping format

The second part should be enabled through configuration.

cziegeler, kpauls, i would give it a try borrowing from existing analysers but i will likely need input from your side to not spend too much time on figuring out details i might have missed.