[db manager] Rename layer style entry when renaming gpkg tables (fixes #21227)

This has been already fixed in master and backported to 3.6 using browser data items.
However the fix can't be directly backported to QGIS 3.4 because in 3.4 geopackage
data item does not support renaming.

Author: wonder-sk

python/plugins/db_manager/db_plugins/gpkg/connector.py

@@ -620,6 +620,9 @@ def renameTable(self, table, new_table):
         if new_table == tablename:
             return True
 
+        quoted_table = self.quoteString(tablename)
+        quoted_table_new = self.quoteString(new_table)
+
         if tablename.find('"') >= 0:
             tablename = self.quoteId(tablename)
         if new_table.find('"') >= 0:
@@ -629,6 +632,12 @@ def renameTable(self, table, new_table):
         self.gdal_ds.ExecuteSQL('ALTER TABLE %s RENAME TO %s' % (tablename, new_table))
         if gdal.GetLastErrorMsg() != '':
             return False
+
+        # also rename any styles referring to this table
+        self.gdal_ds.ExecuteSQL('UPDATE layer_styles SET f_table_name = %s WHERE f_table_name = %s' % (quoted_table_new, quoted_table))
+        if gdal.GetLastErrorMsg() != '':
+            return False
+
         # we need to reopen after renaming since OGR doesn't update its
         # internal state
         self._opendb()