RFR: 8315130: java.lang.IllegalAccessError when processing classlist to create CDS archive [v10]

[Timofei Pushkin]

> If a base class is package-private then its subclasses should have the same package name and defining class loader, otherwise `IllegalAccessError` is thrown when linking a subclass. Currently when dumping a static archive separate `URLClassLoader`s are used for each unregistered classes' source. Thus if two unregistered classes, a package-private base class and a sub class, from the same package reside in different sources `IllegalAccessError` will be thrown when linking the sub class. This can be unexpected because the app could have used a single class loader for both classes and thus not have seen the error — see `DifferentSourcesApp.java` from this patch for an example of such app.
> 
> This patch fixes the issue by using a single class loader for all unregistered classes. CDS does not allow classes with the same name making such solution possible.

Timofei Pushkin has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 15 commits:

 - Empty commit to make GH update the PR
 - Merge remote-tracking branch 'openjdk-jdk/master' into one-loader
 - Implement super overshadowing warning
 - Omit Source classes from archive
 - Remove unused imports
 - Fix indentation
 - Extend ClassFromClasspath test
 - Remove findClass, extend explanation comments
 - Remove unnecessary scoping
 - Don't use URLClassPath
 - ... and 5 more: https://git.openjdk.org/jdk/compare/465c8e65...595756f3

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Changes: https://git.openjdk.org/jdk/pull/24223/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24223&range=09
  Stats: 659 lines in 13 files changed: 475 ins; 122 del; 62 mod
  Patch: https://git.openjdk.org/jdk/pull/24223.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24223/head:pull/24223

PR: https://git.openjdk.org/jdk/pull/24223