[lworld] RFR: 8359370: [lworld] allow instance fields of identity classes to be readable in the prologue phase [v23]

[Vicente Romero]

> Before this fix only strict fields were readable in the prologue phase. The proposed fix should allow any instance fields of identity classes to be readable in the prologue phase. This implies changes in flow analysis as before we were only tracking final and strict fields. There is also some "cooperation" needed in the code to detect cases when reading a field is not allowed in the prologue phase. For example some methods in Resolve don't have all the needed information at the moment they are dealing with some ASTs and part of the processing needs to be done in Attr
> 
> TIA
> 
> This PR is a remake of https://github.com/openjdk/valhalla/pull/1490

Vicente Romero has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 35 commits:

 - Merge branch 'lworld' into JDK-8359370-v2
 - addressing last review comments
 - minor refactoring
 - addressing review comments
 - some documentation
 - moving isEarlyReference to Attr
 - additional changes, more tests
 - addressing review comments
 - removing unnecessary imports
 - addressing review comments
 - ... and 25 more: https://git.openjdk.org/valhalla/compare/59ffa2df...bf2310b7

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Changes: https://git.openjdk.org/valhalla/pull/1523/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1523&range=22
  Stats: 600 lines in 27 files changed: 320 ins; 158 del; 122 mod
  Patch: https://git.openjdk.org/valhalla/pull/1523.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1523/head:pull/1523

PR: https://git.openjdk.org/valhalla/pull/1523