RFR: Merge jdk18 [v2]

[Jesper Wilhelmsson]

> Forwardport JDK 18 -> JDK 19

Jesper Wilhelmsson has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 104 commits:

 - Merge
 - 8279063: Consolidate push and push_if_necessary in PreservedMarks
   
   Reviewed-by: rkennke, mli, tschatzl
 - 8279024: Remove javascript references from clhsdb.html
   
   Reviewed-by: kevinw, sspitsyn
 - Merge
 - 8244670: convert clhsdb "whatis" command from javascript to java
   
   Reviewed-by: sspitsyn, kevinw
 - 8279066: entries.remove(entry) is useless in PKCS12KeyStore
   
   Reviewed-by: mullan
 - Merge
 - 8279060: Parallel: Remove unused PSVirtualSpace constructors
   
   Reviewed-by: mli, sjohanss, tschatzl
 - 8278396: G1: Initialize the BOT threshold to be region bottom
   
   Reviewed-by: tschatzl, sjohanss
 - 8279043: Some Security Exception Messages Miss Spaces
   
   Reviewed-by: weijun
 - ... and 94 more: https://git.openjdk.java.net/jdk/compare/dfb15c3e...70630b7b

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Changes: https://git.openjdk.java.net/jdk/pull/6918/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6918&range=01
  Stats: 18775 lines in 519 files changed: 14457 ins; 3098 del; 1220 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6918.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6918/head:pull/6918

PR: https://git.openjdk.java.net/jdk/pull/6918