Add new migration case of WebMvcConfigurer

[SiBorea]

What's changed?

The origin recipe only handle classes that extend WebMvcConfigurer. In some cases, people return new WebMvcConfigurer() directly as a bean.

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]

Great to see these additional cases covered! Thanks a lot for the continued work on improvements here.

A quick question and two code suggestions before we merge, but otherwise this looks perfect already.

[timtebeek]

Took out the ParameterizedType handling for now, as we're close to a release and didn't want your change to miss out on getting included. If needed we can fold that into the next release. Thanks again!