RFR: 8341142: Maintain a single source file for sun.net.www.protocol.jar.JarFileFactory

[Jaikiran Pai]

Can I please get a review of this change which proposes to keep a single source file for `sun.net.www.protocol.jar.JarFileFactory`?

As noted in https://bugs.openjdk.org/browse/JDK-8341142, the sole difference between the current two sources files is the presence and usage of an additional internal private `urlFor(URL)` method on Windows OS.

The commit in this PR moves ("git mv") the Windows file to the `share/classes` and removes ("git rm") the Unix file. After the move, an conditional check is now added in the private `urlFor(URL)` method to have its implementation be applicable only on Windows.

No new test has been added and existing tier1, tier2 and tier3 tests continue to pass.

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Commit messages:
 - 8341142: Maintain a single source file for sun.net.www.protocol.jar.JarFileFactory

Changes: https://git.openjdk.org/jdk/pull/21245/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21245&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8341142
  Stats: 247 lines in 2 files changed: 7 ins; 239 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/21245.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21245/head:pull/21245

PR: https://git.openjdk.org/jdk/pull/21245