Add support for UTF8 chars in identifiers

[fulghum]

Enables use of UTF8 chars in identifiers, matching PostgreSQL behavior.

Related to #2580

[github-actions]

	Main	PR
covering_index_scan_postgres	1126.62/s	1130.70/s	+0.3%
index_join_postgres	158.92/s	161.25/s	+1.4%
index_join_scan_postgres	209.20/s	208.04/s	-0.6%
index_scan_postgres	12.13/s	12.18/s	+0.4%
oltp_point_select	2380.41/s	2390.06/s	+0.4%
oltp_read_only	1840.78/s	1865.28/s	+1.3%
select_random_points	126.23/s	129.52/s	+2.6%
select_random_ranges	831.10/s	839.26/s	+0.9%
table_scan_postgres	11.75/s	11.94/s	+1.6%
types_table_scan_postgres	5.41/s	5.53/s	+2.2%

[zachmu]

LGTM

[zachmu]

Are there length limits? Are they enforced elsewhere?

[fulghum]

There is a 63 byte limit... but... the docs say that Postgres will automatically truncate longer identifiers to that limit, so we do have some work to do that truncation, but I don't think we want to return false here and reject them outright.

[github-actions]

	Main	PR
Total	42090	42090
Successful	17978	17978
Failures	24112	24112
Partial Successes1	5636	5636

	Main	PR
Successful	42.7132%	42.7132%
Failures	57.2868%	57.2868%

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. ↩