Implement std::fmt::Write for StringViewBuilder to permit non contiguous data to be written

[alamb]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

DataFusion has an optimized version of concat(col1, ...) for StringView added by @devanbenz in apache/datafusion#12224 that uses a StringViewArrayBuilder which is similar but not the same as StringViewBuilder in arrow: https://github.com/apache/datafusion/blob/9bc39a0522840ed90de2a4d23157de2e192cd00f/datafusion/functions/src/string/common.rs#L464-L536

The major differences are:

1. You can call write to incrementally build up each string and then call append_offset to create each string. StringBuilder requires each input to be a single contiguous string to call
2. You can avoid creating the null buffer and pass it in to the finish

Describe the solution you'd like
I would like the APIs in arrow-rs to be sufficiently complete that we could use the arrow-rs versions rather than our own custom versions in DataFusion

Describe alternatives you've considered
StringBuilder allows this like

use std::fmt::Write;
use arrow_array::builder::GenericStringBuilder;
let mut builder = GenericStringBuilder::<i32>::new();

// Write data in multiple `write!` calls
write!(builder, "foo").unwrap();
write!(builder, "bar").unwrap();
// The next call to append_value finishes the current string
// including all previously written strings.
builder.append_value("baz");

let array = builder.finish();
assert_eq!(array.value(0), "foobarbaz");

I think it would be cool to try and follow the same API for StringViewBuilder -- though note that API may be more complicated to ensure we don't get any performance regressions

Additional context

1. See Improve GenericStringBuilder documentation #6372 for better docs of what StringBuilder does
2. Ability to append non contiguous strings to StringBuilder #6347 lists more background

[alamb]

cc @devanbenz in case you are interested in trying to figure out what we need to add to the upstream arrow code to get rid of the custom implementation in DataFusion

[devanbenz]

Just now getting eyes on this FYI

[alamb]

No rush -- I think we have plenty of other things going on -- I would say this is a nice to have in my mind