Allow get query as string for dbapi curson execute method

[rekby]

ydb-sqlalchemy/ydb_sqlalchemy/dbapi/cursor.py

Line 117 in 48cc1c2

def execute(self, operation: YdbQuery, parameters: Optional[Mapping[str, Any]] = None):

Now it can work with some additional mark for ddl queries and it should work fine after switch the dbapi to ydb query service.

[uzhastik]

it would be nice to pass all info about parameters via argument "parameters". now we have parameter types inside YdbQuery