RFR: 8343150: Remove URLClassLoader.getPermissions after JEP 486 integration [v3]

[Jaikiran Pai]

> Can I please get a review of this change which removes the `getPermissions()` method from the `URLClassLoader`? This addresses https://bugs.openjdk.org/browse/JDK-8343150.
> 
> With the SecurityManager implementation removed through JEP 486, this method of the `URLClassLoader` is no longer relevant.
> 
> No new tests have been added. tier1 and tier2 testing is currently in progress.

Jaikiran Pai has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains six commits:

 - specify URLClassLoader to reutrn empty PermissionCollection
 - merge latest from master branch
 - Revert "update the specification of java.security.SecureClassLoader.getPermissions()"
   
   This reverts commit d6220b19a0c4b54d8fc879302baacfa90075f47f.
 - update the specification of java.security.SecureClassLoader.getPermissions()
 - merge latest from master branch
 - 8343150: Remove URLClassLoader.getPermissions after JEP 486 integration

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Changes: https://git.openjdk.org/jdk/pull/22179/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22179&range=02
  Stats: 82 lines in 1 file changed: 0 ins; 73 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/22179.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22179/head:pull/22179

PR: https://git.openjdk.org/jdk/pull/22179