RFR: 8335938: Review XxxBuilder.original and XxxModel.parent [v2]

[Chen Liang]

> Remove unused `Class/Field/Method/CodeBuilder.original()`, and make `Field/Method/CodeModel.parent()` return present only if it's bound (i.e. not buffered transformed). See the CSR for details.

Chen Liang has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains two commits:

 - Merge branch 'master' of https://github.com/openjdk/jdk into fix/builder-original
 - 8335938: Review XxxBuilder.original and XxxModel.parent

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Changes: https://git.openjdk.org/jdk/pull/20177/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20177&range=01
  Stats: 93 lines in 12 files changed: 1 ins; 81 del; 11 mod
  Patch: https://git.openjdk.org/jdk/pull/20177.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20177/head:pull/20177

PR: https://git.openjdk.org/jdk/pull/20177