MDEV-29159 Patch for MDEV-28918 introduces more inconsistency than it solves, breaks usability

1. Store assignment failures on incompatible data types now raise errors if:
- STRICT_ALL_TABLES or STRICT_TRANS_TABLES sql_mode is used, and
- IGNORE is not used

Otherwise, only a warning is raised and the statement continues.

2. Changing the error/warning test as follows:

-ERROR HY000: Illegal parameter data types inet6 and int for operation 'SET'
+ERROR HY000: Cannot cast 'int' as 'inet6' in assignment of `db`.`t`.`col`

so in case of a big table it's easier to see which column has the problem.
The new error text is also applied to SP variables.

sql/sql_insert.h

@@ -27,6 +27,7 @@ int mysql_prepare_insert(THD *thd, TABLE_LIST *table_list,
                          List<Item> &fields, List_item *values,
                          List<Item> &update_fields,
                          List<Item> &update_values, enum_duplicates duplic,
+                         bool ignore,
                          COND **where, bool select_insert);
 bool mysql_insert(THD *thd,TABLE_LIST *table,List<Item> &fields,
                   List<List_item> &values, List<Item> &update_fields,