nested iter should be used for set returning functions as projections only

[jennifersp]

Depends on: dolthub/go-mysql-server#3226

[github-actions]

	Main	PR
covering_index_scan_postgres	325.70/s	331.10/s	+1.6%
index_join_postgres	148.48/s	140.36/s	-5.5%
index_join_scan_postgres	179.04/s	180.26/s	+0.6%
index_scan_postgres	11.27/s	11.25/s	-0.2%
oltp_point_select	2458.55/s	2436.07/s	-1.0%
oltp_read_only	1725.16/s	1716.02/s	-0.6%
select_random_points	111.32/s	109.52/s	-1.7%
select_random_ranges	122.70/s	122.62/s	-0.1%
table_scan_postgres	10.87/s	10.86/s	-0.1%
types_table_scan_postgres	5.05/s	4.95/s	-2.0%

[github-actions]

	Main	PR
Total	42090	42090
Successful	17018	17019
Failures	25072	25071
Partial Successes1	5615	5616

	Main	PR
Successful	40.4324%	40.4348%
Failures	59.5676%	59.5652%

${\color{lightgreen}Progressions (1)}$

tsrf

QUERY: SELECT min(generate_series(1, 3)) OVER() FROM few;

Footnotes

1. These are tests that we're marking as Successful, however they do not match the expected output in some way. This is due to small differences, such as different wording on the error messages, or the column names being incorrect while the data itself is correct. ↩

[Hydrocharged]

LGTM!