RFR: 8173970: jar tool should have a way to extract to a directory [v15]

[Jaikiran Pai]

> Can I please get a review for this patch which proposes to implement the enhancement request noted in https://bugs.openjdk.java.net/browse/JDK-8173970?
> 
> Edit: This PR description has now been updated to match the changes that were done over the course of review inputs that were received for this enhancement.
> 
> The commit in this PR introduces the ability to use `jar` tool to extract the contents of the JAR file to a specific directory of choice. Optional `-C` and `--dir` options are added to the `-x` main operation of the jar tool. The value for these options is expected to be a file path which is expected to be a directory to which the jar will be extracted. When neither `-C` nor `--dir` are used, the extract operation of the jar tool will continue to behave like it did before this enhancement and will extract the jar into the current working directory.
> 
> The commit also includes a jtreg testcase which verifies the usage of this new option.

Jaikiran Pai has updated the pull request incrementally with one additional commit since the last revision:

  update man page after Roger's review

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/2752/files
  - new: https://git.openjdk.org/jdk/pull/2752/files/d4bce414..bb63acba

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=2752&range=14
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=2752&range=13-14

  Stats: 10 lines in 1 file changed: 6 ins; 1 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/2752.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/2752/head:pull/2752

PR: https://git.openjdk.org/jdk/pull/2752