RFR: 8335912: Add an operation mode to the jar command when extracting to not overwriting existing files [v6]

[Henry Jen]

> This PR support a -k, --keep options like tar that allows jar to avoid override existing files.

Henry Jen has updated the pull request incrementally with one additional commit since the last revision:

  Adapt review suggestion

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Changes:
  - all: https://git.openjdk.org/jdk/pull/21141/files
  - new: https://git.openjdk.org/jdk/pull/21141/files/1b7a1f99..f24d965c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21141&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21141&range=04-05

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/21141.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21141/head:pull/21141

PR: https://git.openjdk.org/jdk/pull/21141