RFR: 8114830: (fs) Files.copy fails due to interference from something else changing the file system [v2]

[Brian Burkhalter]

> Throw a `FileSystemException` if attempting to create the target file with `O_EXCL` fails with `EEXIST`.

Brian Burkhalter has updated the pull request incrementally with two additional commits since the last revision:

 - 8114830: Convert test to JUnit 5 and expand coverage
 - 8114830: Extend EEXIST check to directories, links, and devices

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/15141/files
  - new: https://git.openjdk.org/jdk/pull/15141/files/f03dc3e4..a69e8d60

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15141&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15141&range=00-01

  Stats: 96 lines in 2 files changed: 56 ins; 7 del; 33 mod
  Patch: https://git.openjdk.org/jdk/pull/15141.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15141/head:pull/15141

PR: https://git.openjdk.org/jdk/pull/15141