[FLINK-34251][core] Improve diagnostics for closure serialization failures

[liuml07]

This supersedes #26776, which was automatically closed as stale, and the earlier #24205.

JIRA: https://issues.apache.org/jira/browse/FLINK-34251

What is the purpose of the change

ClosureCleaner reports the nested non-serializable object, but complex jobs may reference that object through several operators and third-party classes. The current exception does not show how the object is reached.

This change adds the traversed field path to the exception using the established Java/Spark serialization-debugging format, for example:

java.lang.Object@... is not serializable.
Reference path:
    - object not serializable (class: java.lang.Object)
    - field (class: com.mycompany.LocalMap, name: delegate, type: class java.lang.Object)
    - field (class: com.mycompany.ComplexMap, name: map4, type: class com.mycompany.LocalMap)

Brief change log

• Track fields while recursively cleaning nested objects.
• Report the offending class and each field's declaring class, name, and type, from leaf to root.
• Restore the diagnostic path reliably when recursive cleaning exits.
• Add coverage in ClosureCleanerTest.

Verifying this change

ClosureCleanerTest covers the nested failure and validates the ordered class-and-field path. All 16 tests in the class pass with Java 17. Checkstyle and Java formatting checks pass for the changed files.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): no
• The public API, i.e., is any changed class annotated with @Public(Evolving): no
• The serializers: no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? no
• If yes, how is the feature documented? not applicable

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Generated-by: Pi 0.85.1

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CI report:

• 1930b9e Azure: FAILURE

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