test: show a mismatch for initcap between Spark and DataFusion

[Blizzara]

This PR shows the problem by adding two cases to the test, one using a dash and one using non-ascii letters (from Finnish).

== Results ==
!== Correct Answer - 7 ==       == Spark Answer - 7 ==
 struct<initcap(name):string>   struct<initcap(name):string>
 [James Smith]                  [James Smith]
 [James Smith]                  [James Smith]
![James Ähtäri]                 [James äHtäRi]
 [Michael Rose]                 [Michael Rose]
 [Rames Rose]                   [Rames Rose]
![Robert Rose-smith]            [Robert Rose-Smith]
 [Robert Williams]              [Robert Williams]

Closes #1052

[kazuyukitanimura]

#1052 should be already fixed with the DF44 release. Would you like to rebase and re-trigger this test? @Blizzara

[andygrove]

I tested this PR locally and the test fails. We will likely need to implement a custom version that matches Spark's logic.

Spark                           Comet
![Robert Rose-smith]            [Robert Rose-Smith]

[kazuyukitanimura]

This issue has been outstanding for a while, we should perhaps disable initcap for now

[parthchandra]

Depending on which 'style' guide you follow initcap behavior could or could not capitalize the second part of a hyphenated word (or name).
I doubt if initcap can even be properly defined for English, let alone all other languages.
I feel it would be absolutely fine to either keep the current behavior (and modify the test) or fall back to Spark, whichever the committers prefer. Custom implementation of initcap would be an impossible task.

[kazuyukitanimura]

FYI @Blizzara I included this test in #1276

[Blizzara]

Thanks @kazuyukitanimura !

FWIW, for our internal stuff, I did make a modified copy of DFs initcap, basically just replacing prev_is_alphanumeric = c.is_alphanumeric() with previous_character_space = c == ' ';. I'm sure there are edge cases where it fails to match spark, but for us it felt good enough.

[kazuyukitanimura]

@Blizzara please feel free to reopen once the proper fix is ready