RFR: 8366474: Rename MetaspaceObj::is_shared() to MetaspaceObj::in_aot_cache() [v2]

[Ioi Lam]

> Rename `is_shared()` in `Metaspace` (and various other classes) to `in_aot_cache()` to reflect its true meaning:
> - tests if an object is inside the AOT cache's metaspace region.
> 
> Also various forms of  "shared metaspace" are updated to "aot metaspace"
> 
> Please start your review with allocations.hpp

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

  Removed MetaspaceShared -> AOTMetaspace changes that are intended for https://github.com/openjdk/jdk/pull/27017

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/27016/files
  - new: https://git.openjdk.org/jdk/pull/27016/files/4c68981a..6b8a1b0c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27016&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27016&range=00-01

  Stats: 7 lines in 4 files changed: 0 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/27016.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27016/head:pull/27016

PR: https://git.openjdk.org/jdk/pull/27016