feat: add CherryPickOperation and wire SnapshotManager::Cherrypick

Implements cherry-picking an append or dynamic partition overwrite onto
the current state, with source-snapshot-id and WAP publish tracking,
non-ancestor and replaced-partition validation. SnapshotManager routes
fast-forwardable picks to SetSnapshot, since those produce no snapshot.

Closes the CherryPickOperation item in #637.

Author: shangxinli

src/iceberg/CMakeLists.txt

@@ -119,6 +119,7 @@ set(ICEBERG_SOURCES
     transform.cc
     transform_function.cc
     type.cc
+    update/cherry_pick_operation.cc
     update/delete_files.cc
     update/expire_snapshots.cc
     update/fast_append.cc

src/iceberg/meson.build

@@ -172,6 +172,7 @@ iceberg_sources = files(
     'transform.cc',
     'transform_function.cc',
     'type.cc',
+    'update/cherry_pick_operation.cc',
     'update/delete_files.cc',
     'update/expire_snapshots.cc',
     'update/fast_append.cc',

src/iceberg/test/CMakeLists.txt

@@ -227,6 +227,7 @@ if(ICEBERG_BUILD_BUNDLE)
   add_iceberg_test(table_update_test
                    USE_BUNDLE
                    SOURCES
+                   cherry_pick_operation_test.cc
                    delete_files_test.cc
                    expire_snapshots_test.cc
                    fast_append_test.cc