Fix incorrect path computation for Spring API endpoints

[adrilo]

What's changed?

The current logic did not cover the case where a RequestMapping with a path was defined on the Controller class, and no paths were defined in the *Mapping at the method level.

Checklist

• I've added unit tests to cover both positive and negative cases
• I've read and applied the recipe conventions and best practices
• I've used the IntelliJ IDEA auto-formatter on affected files

[timtebeek]

Thanks a lot for the fix here @adrilo ; Out of curiosity: did you already run this recipe through the Moderne CLI against local projects?

I'll fix the test failures separately before we merge; Those came in after

• Make FindMissingTypes stricter for method invocations rewrite#4688