RFR: 8271186: Add UL option to replace newline char [v4]

[Yasumasa Suenaga]

On Wed, 25 Aug 2021 03:47:47 GMT, Ioi Lam <iklam at openjdk.org> wrote:

> I don't think your current implementation has the right abstraction

Agree, I think we can (should) improve more. Its improvement is not for `LogSocketStream` but also for `LogStd{out,err}Output`.
As we discussed in CSR about stdout/err, we will work for them in next step. But they extend `LogFileStreamOutput` directly. So I want to refactor it before next step.

Anyway I moved `foldmultiline` handling into `LogFileOutput` in new commit.

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PR: https://git.openjdk.java.net/jdk/pull/4885