[C] Add convenience functions

[paleolimbot]

...based on writing some nanoarrow code in the R package, https://github.com/geoarrow/geoarrow-cpp/ , and https://github.com/paleolimbot/minigpkg/

A few that may be nice are:

• ArrowBufferAppendStringView() (i.e., ArrowBufferAppendStringView(buffer, ArrowCharView("some string");)
• ArrowBufferAppendBufferView() (i.e., ArrowBufferAppendBufferView(buffer, some_array_view->buffer_views[1]))
• ArrowArrayMove(struct ArrowArray* src, struct ArrowArray* dst), ArrowSchemaMove(struct ArrowSchema* src, struct ArrowSchema* dst), and ArrowArrayStreamMove(struct ArrowArrayStream* src, struct ArrowArrayStream* dst) (more readable than memcpy(dst, src, sizeof(struct ArrowSomething); src->release = NULL;)

Another thing that came up is a pattern for unsafe appends. The buffer appenders in the ArrowBufferAppendInt32() family all check and possibly reallocate; the array appenders in the ArrowArrayAppendInt() family do a switch() on type and range checks to help prevent implicit overflow. Adding more convenience around this like maybe ArrowBufferAppendInt32Unsafe() or ArrowArrayInt32AppendInt32Unsafe() is probably very verbose and isn't that hard to work around. I could be convinced either way on whether they should exist or not.

[lidavidm]

At the risk of turning into a general C utilities library, I've found having a string builder utility also useful in the ADBC SQLite driver I'm working on.

[paleolimbot]

I forget exactly where I did that but I definitely did it too at least once (I think I was building error messages).

[paleolimbot]

Oh! It's was in nanoarrow itself but I changed approaches...it was the first draft of the ArrowSchemaToString().