Add support for Transaction.update_statistics() (#1831)

# Rationale for this change

Addd a new API `Transaction.update_statistics()` to use the existing
transaction instead of a brand new one.

# Are these changes tested?

I extended
`tests/integration/test_statistics_operations.py::test_manage_statistics`
to test the new API.

# Are there any user-facing changes?

Users can now update statistics files within an ongoing transaction.

Author: srilman

pyiceberg/table/__init__.py

@@ -438,6 +438,15 @@ def update_snapshot(self, snapshot_properties: Dict[str, str] = EMPTY_DICT) -> U
         """
         return UpdateSnapshot(self, io=self._table.io, snapshot_properties=snapshot_properties)
 
+    def update_statistics(self) -> UpdateStatistics:
+        """
+        Create a new UpdateStatistics to update the statistics of the table.
+
+        Returns:
+            A new UpdateStatistics
+        """
+        return UpdateStatistics(transaction=self)
+
     def append(self, df: pa.Table, snapshot_properties: Dict[str, str] = EMPTY_DICT) -> None:
         """
         Shorthand API for appending a PyArrow table to a table transaction.

tests/integration/test_statistics_operations.py

@@ -82,3 +82,10 @@ def create_statistics_file(snapshot_id: int, type_name: str) -> StatisticsFile:
         update.remove_statistics(add_snapshot_id_1)
 
     assert len(tbl.metadata.statistics) == 1
+
+    with tbl.transaction() as txn:
+        with txn.update_statistics() as update:
+            update.set_statistics(statistics_file_snap_1)
+            update.set_statistics(statistics_file_snap_2)
+
+    assert len(tbl.metadata.statistics) == 2