Align UDF names to lowercase or uppercase

[edmondop]

Describe the bug

As a part of performing this change, @jayzhan211 recommended to use min and max as a default name for the new UDFs rather than the lowercase. However, performing this change makes test fails because in several places we use MAX and MIN, for example:

https://github.com/apache/datafusion/blob/0332eb569a5428ac385fe892ce7b5fb40d52c8c0/datafusion/sqllogictest/test_files/tpch/q15.slt.part use MAX uppercase that would cause build failure when comparing LogicalPlan like in the following build:
https://github.com/apache/datafusion/actions/runs/10215600305/job/28265554129?pr=11013

In the rust tests as well we use avg but MAX, so we need to update those tests as well

datafusion/datafusion/core/src/dataframe/mod.rs

Line 2059 in 0332eb5

"| c1 | MIN(aggregate_test_100.c12) | MAX(aggregate_test_100.c12) | avg(aggregate_test_100.c12) | sum(aggregate_test_100.c12) | count(aggregate_test_100.c12) | count(DISTINCT aggregate_test_100.c12) |",

To Reproduce

No response

Expected behavior

No response

Additional context

I have not verified if MAX and MIN are the only UDF for which we use uppercase rather than lowercase. I personally prefer to have all SQL KEYWORDS (including UDF names) uppercase for readability

[jayzhan211]

Sadly this is the last name to be lowercase, others are already converted. I don't have strong preference on upper case or lower case as long as they are all consistent

[edmondop]

Agreed,I think it's better to read

SELECT MAX(stuff) rather than SELECT max(stuff) and keep the lowercase for columns and non-keyword

[jayzhan211]

Agreed,I think it's better to read

SELECT MAX(stuff) rather than SELECT max(stuff) and keep the lowercase for columns and non-keyword

The lowercase/uppercase conversion is quite painful since you need to change many places. Especially for dataframe test

It is worth to find out an easy way to update the dataframe test beforehand #10373