use sql.Row and sql/type.Compare for dolt_diff table

[zachmu]

This was one of the few non-test places we were instantiating and comparing noms types values. Converted it to use the native SQL types Compare method

[coffeegoddd]

@zachmu DOLT

read_tests	from_latency	to_latency	percent_change
covering_index_scan	0.55	0.55	0.0
groupby_scan	9.91	9.91	0.0
index_join	1.86	1.86	0.0
index_join_scan	1.37	1.37	0.0
index_scan	21.89	22.28	1.78
oltp_point_select	0.27	0.27	0.0
oltp_read_only	5.28	5.28	0.0
select_random_points	0.54	0.54	0.0
select_random_ranges	0.56	0.55	-1.79
table_scan	22.28	22.28	0.0
types_table_scan	66.84	66.84	0.0

write_tests	from_latency	to_latency	percent_change
oltp_delete_insert	6.32	6.32	0.0
oltp_insert	3.07	3.13	1.95
oltp_read_write	11.24	11.45	1.87
oltp_update_index	3.19	3.19	0.0
oltp_update_non_index	3.13	3.13	0.0
oltp_write_only	6.09	6.09	0.0
types_delete_insert	6.79	6.79	0.0

[fulghum]

LGTM!

[coffeegoddd]

@zachmu DOLT

[coffeegoddd]

@zachmu DOLT

test_name	from_latency_p95	to_latency_p95	percent_change
tpcc-scale-factor-1	61.08	61.08	0.0

test_name	from_server_name	from_server_version	from_tps	to_server_name	to_server_version	to_tps	percent_change
tpcc-scale-factor-1	dolt	ae67607	37.37	dolt	7aa20e3	37.71	0.91