add helper function for execute_values

Make psycopg2's convenience function accessible through
the cursor.

nominatim/tokenizer/legacy_icu_tokenizer.py

@@ -9,8 +9,6 @@ import re
 from textwrap import dedent
 from pathlib import Path
 
-import psycopg2.extras
-
 from nominatim.db.connection import connect
 from nominatim.db.properties import set_property, get_property
 from nominatim.db.utils import CopyBuffer
@@ -359,8 +357,7 @@ class LegacyICUNameAnalyzer:
         to_delete = existing_phrases - new_phrases
 
         if to_delete:
-            psycopg2.extras.execute_values(
-                cursor,
+            cursor.execute_values(
                 """ DELETE FROM word USING (VALUES %s) as v(name, in_class, in_type, op)
                     WHERE word = name and class = in_class and type = in_type
                           and ((op = '-' and operator is null) or op = operator)""",

nominatim/tokenizer/legacy_tokenizer.py

@@ -370,8 +370,7 @@ class LegacyNameAnalyzer:
             to_delete = existing_phrases - norm_phrases
 
             if to_add:
-                psycopg2.extras.execute_values(
-                    cur,
+                cur.execute_values(
                     """ INSERT INTO word (word_id, word_token, word, class, type,
                                           search_name_count, operator)
                         (SELECT nextval('seq_word'), ' ' || make_standard_name(name), name,
@@ -381,8 +380,7 @@ class LegacyNameAnalyzer:
                     to_add)
 
             if to_delete and should_replace:
-                psycopg2.extras.execute_values(
-                    cur,
+                cur.execute_values(
                     """ DELETE FROM word USING (VALUES %s) as v(name, in_class, in_type, op)
                         WHERE word = name and class = in_class and type = in_type
                               and ((op = '-' and operator is null) or op = operator)""",