[lworld] RFR: JDK-8269023 [lworld] L/Q<type> support [v3]

[David Simms]

> Merge work from lqagain branch

David Simms has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 24 commits:

 - Merge branch 'lworld' of https://git.openjdk.java.net/valhalla into close_lqagain
 - 8218159: ValueBootstrapMethods.isSubstitutable should not filter synthetic fields
 - 8268981: [lworld] UnifiedPrimitiveClassNestHostTest.java should test with the primary mirror
 - 8268980: [lword] Fix Class::descriptorString to return L-descriptor for primitive ref type
 - Merge lworld
   
   Merge lworld @jdk-18+2
 - 8268908: Update test/jdk/valhalla/valuetypes tests to prepare for jtreg 6 and other clean up
 - 8268656: [lqagain] A few code chunks dealing with dual class scheme still left in
 - 8268358: [lworld] toString for primitive class should return `ClassName at hash`
   
   Reviewed-by: rriggs
 - 8268584: [lqagain] Javac tests should not needlessly hardcode toString() output
 - 8267597: [lworld] Withdraw all support for bifurcated class generation for primitive classes
   8268527: [lqagain] langtool tests need tweaks to run properly in an universe where -XDunifiedValRefClass is the default
 - ... and 14 more: https://git.openjdk.java.net/valhalla/compare/fab7d7a1...9579e93b

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

Changes: https://git.openjdk.java.net/valhalla/pull/453/files
 Webrev: https://webrevs.openjdk.java.net/?repo=valhalla&pr=453&range=02
  Stats: 4537 lines in 188 files changed: 1709 ins; 1987 del; 841 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/453.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/453/head:pull/453

PR: https://git.openjdk.java.net/valhalla/pull/453