[jdk19] RFR: 8287809: Revisit implementation of memory session [v5]

[Maurizio Cimadamore]

> This is a JDK 19 clone of: https://github.com/openjdk/jdk/pull/9017

Maurizio Cimadamore has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains ten commits:

 - Merge branch 'master' into memory_session_cleanup
 - Fix ambiguity between session vs. base session
 - Revert implicit vs. heap session changes
 - Unify heap vs. implicit scopes
 - Merge branch 'master' into memory_session_cleanup
 - Fix issue in Direct-X-Buffer template
 - Simplify and drop the state class
 - Add missing files
 - Initial push

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Changes: https://git.openjdk.org/jdk19/pull/22/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk19&pr=22&range=04
  Stats: 484 lines in 24 files changed: 56 ins; 107 del; 321 mod
  Patch: https://git.openjdk.org/jdk19/pull/22.diff
  Fetch: git fetch https://git.openjdk.org/jdk19 pull/22/head:pull/22

PR: https://git.openjdk.org/jdk19/pull/22