[FLINK-40556][table] Support UUID value literals backed by byte[] values

[raminqaf]

What is the purpose of the change

UuidType allows both UUID and byte[] as conversion classes, so a ValueLiteralExpression can legally hold a UUID literal internally as a byte[]. ValueLiteralExpression#getValueAs(UUID.class) didn't handle that case and returned empty, so both asSerializableString and ExpressionConverter threw NoSuchElementException/IllegalStateException instead of producing a literal.

Brief change log

• Added a byte[] to UUID conversion arm in ValueLiteralExpression#getValueAs, matching the existing coercion pattern for LocalDate, Instant, and other multi-representation types.
• Fixes both affected call sites (asSerializableString and ExpressionConverter#visit) with a single change, since both go through getValueAs.

Verifying this change

This change added tests and can be verified as follows:

• ExpressionTest#testUuidValueLiteralExtraction and #testUuidAsSerializableString are parameterized over a direct UUID literal and a byte[]-bridged literal.
• ExpressionConverterTest#testUuidLiteral and #testUuidLiteralFromBytes cover the same two cases through the planner's RexNode conversion path.
• All four byte[]-backed cases reproduce the original exception before the fix and pass after it.

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

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Generated-by: Claude Code (Sonnet 5)

[twalthr]

LGTM

[flinkbot]

CI report:

• eb41e68 Azure: SUCCESS

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