RFR: 8294193: Files.createDirectories throws FileAlreadyExistsException for a symbolic link whose target is an existing directory [v3]

[Jaikiran Pai]

> Can I please get a review of this change which proposes to fix the issue noted in https://bugs.openjdk.org/browse/JDK-8294193?
> 
> As discussed in a related PR https://github.com/openjdk/jdk/pull/10266#issuecomment-1246800456, this is a genuine bug in the `java.nio.file.Files.createDirectories` implementation. The commit in this PR fixes that by making sure that links are followed when checking if a `Path` is a directory during the creation of directories in the `createDirectories` implementation. The `private` method which is changed in this PR is only used in the `Files.createDirectories` and no other place, so this change should not impact any other code. Additionally a new test has been added to reproduce the issue and verify the fix.
> tier1, tier2 and tier3 tests passed with this change.

Jaikiran Pai has updated the pull request incrementally with one additional commit since the last revision:

  review comments for test

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Changes:
  - all: https://git.openjdk.org/jdk/pull/10383/files
  - new: https://git.openjdk.org/jdk/pull/10383/files/e918d33c..350b3f87

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10383&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10383&range=01-02

  Stats: 14 lines in 1 file changed: 2 ins; 1 del; 11 mod
  Patch: https://git.openjdk.org/jdk/pull/10383.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10383/head:pull/10383

PR: https://git.openjdk.org/jdk/pull/10383