RFR: 8356493: (fs) SecureDirectoryStream missing some capabilities

[Brian Burkhalter]

Add several methods to `java.nio.file.SecureDirectoryStream`.

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Commit messages:
 - 8356493: (fs) SecureDirectoryStream missing some capabilities

Changes: https://git.openjdk.org/jdk/pull/26950/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26950&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8356493
  Stats: 666 lines in 6 files changed: 654 ins; 4 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/26950.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26950/head:pull/26950

PR: https://git.openjdk.org/jdk/pull/26950