RFR: 8293792: runtime/Dictionary/ProtectionDomainCacheTest.java fails with FileAlreadyExistsException: /tmp

[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-8293792?

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.

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Commit messages:
 - newline at end of test file
 - fix whitespace issue in test
 - 8293792: Follow symlinks in Files.createDirectories for checking file existence

Changes: https://git.openjdk.org/jdk/pull/10383/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10383&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8293792
  Stats: 79 lines in 2 files changed: 78 ins; 0 del; 1 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