Add recipe to migrate JUnit 4 ExternalResource rules using jupiter-migrationsupport

[amishra-u]

Implements HandleExternalResourceRules recipe to migrate JUnit 4 ExternalResource-based @rule and @ClassRule fields to JUnit 5 by adding @ExtendWith(ExternalResourceSupport.class) from
junit-jupiter-migrationsupport. This provides a migration path for rules like TemporaryFolder and GrpcCleanupRule that extend ExternalResource but don't have direct JUnit 5 equivalents.

Changes:

• Add HandleExternalResourceRules recipe to detect ExternalResource-based rules
• Add helper methods to Junit4Utils for checking @Rule/@ClassRule annotations
• Add junit-jupiter-migrationsupport and grpc-testing dependencies for testing
• Add comprehensive test coverage for field and method-based rules

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 @amishra-u ; good to see these rules flow back to the project to convert any left over cases beyond what was covered already.

I've applied a few small changes, mostly to add preconditions and reduce the usage of Annotated.Matcher when service(AnnotationService) ought to be enough.