Cleanup / overhaul `StringViewArrayBuilder` and related types

[neilconway]

Is your feature request related to a problem or challenge?

StringViewArrayBuilder / StringArrayBuilder / LargeStringArrayBuilder has a fairly special-purpose API; it is basically only well-suited to use by concat and concat_ws, which is indeed the only place that uses it today. That makes it particularly odd that it is pub, not pub(crate).

In addition, there are a bunch of places where we use Arrow's StringBuilder / StringViewBuilder that would benefit from a better API: by passing the NULL bitmap to finish(), we can avoid the overhead of constructing the NULL bitmap iteratively.

Describe the solution you'd like

1. Rename StringViewArrayBuilder -> ConcatStringViewBuilder, and so on for the other two functions.
2. Make the Concat[...]Builder types pub(crate)
3. Add a new family of specialized builders (StringArrayBuilder, LargeStringArrayBuilder, StringViewArrayBuilder), with an API like with_capacity, append_value(&str), append_placeholder(), finish(Option<NullBuffer>). This should be pub(crate).
4. Switch most of the places where we use Arrow's StringBuilder to use one of the new bulk-NULL builders. This should cover call-sites like initcap, reverse, translate, substrindex, replace, lpad/rpad, repeat, min_max_bytes, first_last/state, concat_elements_utf8view, lower, and upper.

Describe alternatives you've considered

No response

Additional context

No response