ARROW-6055: [C++] Refactor arrow::io hdfs to implement arrow::filesystem#5709

bkietz wants to merge 7 commits into

apache:masterapache/arrow:masterfrom

bkietz:6055-Refactor-arrow-io-hdfs-h-bkietz/arrow:6055-Refactor-arrow-io-hdfs-h-Copy head branch name to clipboard