Add DictCursor support

[KageyamaRuka]

Is your feature request related to a problem? Please describe.
when fetched with cursor, it just return tuple list, and that might be inefficient to deal with, sometimes a DictCursor that returns list of Dict[FieldName, value] might be better

Describe the solution you'd like
DictCursor that returns list of Dict[FieldName, value], like pymysql or psycopg
https://pymysql.readthedocs.io/en/latest/modules/cursors.html
https://www.psycopg.org/docs/extras.html