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

[Ioi Lam]

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.

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Depends on: https://git.openjdk.org/jdk/pull/27017

Commit messages:
 - 8366477: Refactor AOT-related flag bits in klass.hpp

Changes: https://git.openjdk.org/jdk/pull/27018/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27018&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8366477
  Stats: 54 lines in 4 files changed: 20 ins; 10 del; 24 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