Fixes issues with incorrect indentation

[dmikusa]

Summary

Given a situation where bytes were written to the logger that do not end with a newline, then another set of bytes are written, the second set of bytes would be indented incorrectly. For example. First, write some-data, then write more-data\nindent. It should log some-datamore-data\n indent, but it actually writes some-data more-data\n indent. There should not be an indent between the two writes because we only indent after a newline.

Use Cases

This caused issues when indenting output from commands like mvn and cargo.

This PR resolves the issue and adds tests to confirm correct output.

Checklist

• I have viewed, signed, and submitted the Contributor License Agreement.
• I have linked issue(s) that this PR should close using keywords or the Github UI (See docs)
• I have added an integration test, if necessary.
• I have reviewed the styleguide for guidance on my code quality.
• I'm happy with the commit history on this PR (I have rebased/squashed as needed).