[LANG-1651] Add utility method to detect public static final fields

[Sara-77163]

Hello @garydgregory

This PR addresses LANG-1651: https://issues.apache.org/jira/projects/LANG/issues/LANG-1651?filter=allopenissues

This PR adds a new utility method FieldUtils.isPublicStaticFinal(Field)
and corresponding unit tests.

The method checks whether a Field has public, static and final modifiers,
which is useful when identifying constant-like fields via reflection.

This utility centralizes a commonly repeated reflection check, improving readability,
avoiding duplicated modifier logic, and aligning with existing helpers in FieldUtils.
It can be used, for example, when scanning classes via reflection to identify public constants.

All tests pass locally using mvn.

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[garydgregory]

Hello @Sara-77163

Thank you for your interest in the Commons project.

I think you might have missed this from the Jira ticket: "Potentially use in reflection operations". This PR doesn't make use of the new API, so it doesn't seem needed. I could be missing something of course.

[garydgregory]

Closing.