fix: skip finalizing anonymous class fields in FinalizeLocalVariables

[AlejandroBertolo]

What's changed?

Variables identified as fields of anonymous classes will be skipped in FinalizeLocalVariables recipe.

What's your motivation?

Fixes #181

Anything in particular you'd like reviewers to focus on?

There is perhaps a better way of identifying anonymous classes.

Anyone you would like to review specifically?

@timtebeek

Checklist

• I've added unit tests to cover both positive and negative cases
• I've added the license header to any new files through ./gradlew licenseFormat
• no new files were added
• I've used the IntelliJ IDEA auto-formatter on affected files

[AlejandroBertolo]

Found a simpler way to identify anonymous class parents, as seen in MissingOverrideAnnotation recipe.
Should do the trick.

[timtebeek]

Thanks for the quick work on this!