RFR: 8341551: Revisit jdk.internal.loader.URLClassPath.JarLoader after JEP 486

[Jaikiran Pai]

Can I please get a review of this change which proposes to address https://bugs.openjdk.org/browse/JDK-8341551? 

The primary work in this PR is the specification of the previously existing `sun.misc.URLClassPath.disableJarChecking` system property and how the internal implementation of `java.net.URLClassLoader` treats it. The complete details about this property is available in the CSR for this change here https://bugs.openjdk.org/browse/JDK-8345394.

A new jtreg test has been introduced to exercise the usage of this system property.

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Commit messages:
 - introduce a test for the sun.misc.URLClassPath.disableJarChecking system property
 - 8341551: Revisit jdk.internal.loader.URLClassPath.JarLoader after JEP 486

Changes: https://git.openjdk.org/jdk/pull/22545/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22545&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8341551
  Stats: 151 lines in 2 files changed: 144 ins; 2 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/22545.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22545/head:pull/22545

PR: https://git.openjdk.org/jdk/pull/22545