RFR: 8366477: Refactor AOT-related flag bits in klass.hpp [v2]

[Ioi Lam]

> This PR is one (of many) steps in [JDK-8366473](https://bugs.openjdk.org/browse/JDK-8366473) (Refactor CDS source code with new AOT terminology):
> 
> 1. Rename from `Klass::_shared_class_flags` to `Klass::_aot_class_flags`
> 2. Move `_has_aot_safe_initializer` and `_is_runtime_setup_required` from `InstanceKlassFlags` (has run out of bits) to here (we still have 7 extra bits left), to accommodate future `@AOTXXX` annotations.

Ioi Lam has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:

 - Merge branch '8366475-rename-metaspace-shared-to-aot-metaspace' into 8366477-refactor-aot-related-flag-bits-in-klass-hpp
 - 8366477: Refactor AOT-related flag bits in klass.hpp

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/27018/files
  - new: https://git.openjdk.org/jdk/pull/27018/files/709d3d23..08d02072

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27018&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27018&range=00-01

  Stats: 2 lines in 2 files changed: 0 ins; 2 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/27018.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27018/head:pull/27018

PR: https://git.openjdk.org/jdk/pull/27018