RFR: 8315241: (fs) Move toRealPath tests in java/nio/file/Path/Misc.java to separate JUnit 5 test

[Brian Burkhalter]

Move toRealPath() tests from Misc.java to ToRealPath.java.

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Commit messages:
 - 8315241: (fs) Move toRealPath tests in java/nio/file/Path/Misc.java to separate JUnit 5 test

Changes: https://git.openjdk.org/jdk/pull/15474/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15474&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8315241
  Stats: 334 lines in 2 files changed: 191 ins; 141 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/15474.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15474/head:pull/15474

PR: https://git.openjdk.org/jdk/pull/15474