[common] Add shared-shredding write helpers for MAP columns

[lxy-9602]

Purpose

This is a sub-PR for MAP shared-shredding write support. The full shared-shredding write path will be wired in later PRs.

• Add MapSharedShreddingContext to maintain cross-file shared-shredding state and compute the next physical column width K.
• Add MapSharedShreddingFieldDict to assign stable field ids for MAP keys within a shared-shredding field.
• Add MapSharedShreddingColumnAllocator to allocate MAP entries into physical shared columns for each row.
  • This is currently a simple temporary implementation based on row order.
  • A later version will support a more sophisticated LRU-style allocation strategy.
• Add MapSharedShreddingRowConverter to lazily wrap logical InternalRow records and convert shared-shredding MAP fields into their physical representation only when those fields are accessed.

Related design:
https://cwiki.apache.org/confluence/display/PAIMON/PIP-43%3A+Columnar+Storage+Optimization+for+MAP+Type+in+Paimon

Tests

mvn -pl paimon-common -am -Pfast-build -DfailIfNoTests=false \
  -Dtest=MapSharedShreddingColumnAllocatorTest,MapSharedShreddingContextTest,MapSharedShreddingFieldDictTest,MapSharedShreddingRowConverterTest test

[JingsongLi]

Looks no problem, wait CI.

[JingsongLi]

+1