arrow

ARROW-12359: [C++] Deprecate FileSystem::OpenAppendStream

This function is poorly supported accross filesystems and is not generally useful for the kind of data that Arrow accesses.

Closes #10874 from pitrou/ARROW-12359-deprecate-open-append-stream

Authored-by: Antoine Pitrou <antoine@python.org>
Signed-off-by: Antoine Pitrou <antoine@python.org>