Implement native stringview support for BTRIM

[Kev1n8]

Which issue does this PR close?

Closes #11835

Rationale for this change

What changes are included in this PR?

The changes mainly lie in datafusion/functions/string/common.rs, where I broke generic_trim up to deal with 2 conditions (whether to use Utf8View or not). An additional parameter is also added to indicate the datatype. I also temporarily adjusted LTRIM and RTRIM to work through the process. If my implementation is considered a good practice, I would like to open follow-on PRs to have LTRIM and RTRIM support Utf8View natively.

And some tests were also added to string_view.slt covering the Utf8View support of BTRIM.

Are these changes tested?

yes

Are there any user-facing changes?

no

[Kev1n8]

Just an info: I tried combining the two functions string_view_trim and string_trim by treating StringArray and StringViewArray as something like dyn Array + ArrayAccessor. But the trait of value() between these two actually differs. StringArray impls value() by impl ArrayAccessor while it comes with no ArrayAccessor of StringViewArray, it is instead directly impl.

[alamb]

Thank you @Kev1n8 -- I think this PR is an improvement for sure.

[alamb]

This implementation is an improvement -- however, it will now copy the string values to a new StringArray

I think if the function generated StringView output directly it would be possible to avoid all string copies (and only adjust the views).

I can file this as a follow on optimization idea.

I noticed this on #11790