Fixes #2866

This PR fixes a bug in BaseConfigurator where the generic type information declared by a setter could be replaced by the corresponding getter's generic type during attribute resolution.

When a Jenkins plugin declared a broader or wildcard generic type in its setter (for example, List<? extends PriorityStrategy>) but exposed a narrower collection type from its getter, JCasC would use the getter's generic type in place of the setter's declared generic type. As a result, polymorphic HeteroDescribable collections could no longer be configured correctly.

describe() now treats the setter's generic signature as the source of type information. The getter is only used to recover generic information when the setter provides no meaningful generic type.

Testing

• Added regression tests to BaseConfiguratorTest covering mismatched getter/setter collection signatures.
• Manually verified the fix using a Jenkins instance configured with the Priority Sorter plugin. A configuration that previously failed with an UnknownAttributesException now loads successfully.

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