[core] Manage manifest extra file lifecycle

[leaves12138]

Purpose

Follow up on #9845 with manifest extra-file lifecycle management, extracted from #9743.

• Delete an unreferenced manifest together with its explicitly recorded extra files, including custom sidecar names.
• Use the manifest metadata when cleaning newly created manifests after a failed commit or merge; keep reused manifests intact.
• Include extra files in snapshot/tag/changelog retention sets. Preserve shared extra files that are still referenced by retained manifests.
• Keep orphan cleanup based on explicit references rather than names inferred from a manifest suffix.

This change uses the existing _EXTRA_FILES field. It does not introduce new table options, enable sidecar generation, change the file format, or add scan pruning. Writer and reader integration remain follow-ups.

Tests

Java 8: 159 tests passed with Checkstyle and Spotless enabled.

Coverage includes metadata round-trips, deletion of only explicitly referenced files, shared-file retention, failed delta/changelog/merge commit cleanup, snapshot and tag retention, orphan cleanup, and existing manifest rewrite failures.

mvn -B -ntp -nsu -pl paimon-codegen-loader -am -DskipTests package
mvn -B -ntp -nsu -pl paimon-core -am -DwildcardSuites=none -DfailIfNoTests=false -Dflink.forkCount=2 \
  -Dtest=ManifestSidecarLifecycleTest,ManifestFileTest,ManifestFileMetaSerializerTest,ManifestRewriteCleanupTest,ExpireSnapshotsTest,LocalOrphanFilesCleanTest test

[JingsongLi]

+1