RFR: JDK-8274172: Convert JavadocTester to use NIO [v2]

[Jonathan Gibbons]

On Thu, 23 Sep 2021 16:26:36 GMT, Pavel Rappo <prappo at openjdk.org> wrote:

>> That example is somewhat overkill, since it handles symlinks as well, which we don't need.
>
> Agreed on symlinks. What I was referring to is using Files.copy to copy directories, not Files.createDirectories to create them.

I guess I find it non-obvious to use `Files.copy` to create an empty directory, without copying its contents.  That being said, the latest commit uses the example code, now in `ToolBox` which is a better home for this method.

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PR: https://git.openjdk.java.net/jdk/pull/5644