## What changes were proposed in this pull request?

This replaces uses of `TextOutputFormat` with an `OutputStream`, which will either write directly to the filesystem or indirectly via a compressor (if so configured). This avoids intermediate buffering.

The inverse of this (reading directly from a stream) is necessary for streaming large JSON records (when `wholeFile` is enabled) so I wanted to keep the read and write paths symmetric.

## How was this patch tested?

Existing unit tests.

Author: Nathan Howell <nhowell@godaddy.com>

Closes #16089 from NathanHowell/SPARK-18658.