Improve performance of *TRIM functions for StringViewArray

[Kev1n8]

Is your feature request related to a problem or challenge?

StringView provides us a way to directly modify views of an array instead of generating a new StringArray when it comes to string operations like substr, which was done in #12044. I think we can play a similar trick in trim.

Describe the solution you'd like

I've looked into the implementation of general_trim, it uses the str::trim_xxx_matches methods the obtain the "substring". Furthermore, inside the str::trim_xxx_matches method, it first computes the [start, end) boundary and slices the str. The index here is useful for modifying views. Unfortunately, currently the feature Pattern it uses is unstable.

Describe alternatives you've considered

I'm not very sure what alternatives we have. Perhaps either implement our own trim or wait until Pattern is stable in Rust.

Additional context

No response

[Rachelint]

Seems we can get the index through this way:

• Convert the originanl str1 to ptr1(*const [u8]) first.
• Then we use trim_xxx_matches first to get the str2.
• Convert the str2 to ptr2(*cosnt [u8]), and we get the index through ptr2 - ptr1?

Maybe I can try it.

[Kev1n8]

Sounds great! @Rachelint

[Rachelint]

take

[Rachelint]

Finally, after reminding from @alamb , I found we can get the index in safe way, detail can see:
https://github.com/Rachelint/arrow-datafusion/blob/f8174626e47d147e90c6715f5052ccfa269f0493/datafusion/functions/src/string/common.rs#L80