Add query_raw() method to connection object

Summary: skip the orderdict / selectresult stuff and return lists of dicts.

Test Plan: quality time with a stopwatch

Reviewers: carl, neil

CC: dashboard

Maniphest Tasks: T8611

Differential Revision: http://grizzly.memsql.com/D5212
Add query_raw() method to connection object

Summary:
skip the orderdict / selectresult stuff and return lists of dicts.

Immutable ordered dict for Row class

a naiver-er OrderedDict with much lower insert penalty at the expense of O(n) deletion and unspecified sadtown behavior on large dicts. Since we mostly work with small immutable dicts, this works approximately 3X faster on modest resut sets, eg 10 columns X 500 rows.

Test Plan:
quality time with a stopwatch

pytest

Reviewers: carl, neil

Reviewed By: carl

CC: dashboard

Maniphest Tasks: T8611

Differential Revision: http://grizzly.memsql.com/D5212