RFR: 8350550: Preload classes from AOT cache during VM bootstrap [v4]

[Ioi Lam]

> This PR loads the classes for the boot/platform/app loaders with `AOTLinkedClassBulkLoader::preload_classes()`. This happens at the very beginning of `vmClasses::resolve_all()`, before any Java code is executed. 
> 
> - We essentially iterate over all the classes inside the `AOTLinkedClassTable` and adds them into the system dictionary using the new method `SystemDictionary::preload_class()`.
> - `SystemDictionary::preload_class(..., k)` is lightweight because it's called in a single thread after all super types of `k` have been loaded. So most of the complicated work (such as place holders, circularity detection, etc) in `SystemDictionary::resolve_or_null(..., k)` can be skipped. We also don't need to call into `ClassLoader::load_class()` as the boot/platform/app loaders are well-behaved.
> - In the assembly phase, we record the mirror, package, protection domain, code source, etc, of these classes. So there's no need to programmatically create them in the production run. See `HeapShared::copy_java_mirror()` and also changes in ClassLoader.java and SecureClassLoader.java.

Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:

  @DanHeidinga comment - add test: user enum types are not initialized in assembly phase

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Changes:
  - all: https://git.openjdk.org/jdk/pull/26375/files
  - new: https://git.openjdk.org/jdk/pull/26375/files/ecc2581d..f12ad484

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=26375&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=26375&range=02-03

  Stats: 43 lines in 1 file changed: 43 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/26375.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26375/head:pull/26375

PR: https://git.openjdk.org/jdk/pull/26375