RFR: JDK-8309503: Improve javax.lang.model tests for JEP 445 [v3]

[Joe Darcy]

> Improve testing methodology for unnamed classes in javax.lang.model, including coverage of binary names.

Joe Darcy has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:

 - Refine semantics of what is tested.
 - Merge branch 'master' into JDK-8309503
 - Improve test to make sure some checking is done.
 - JDK-8309503: Improve javax.lang.model tests for JEP 445

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Changes:
  - all: https://git.openjdk.org/jdk/pull/14321/files
  - new: https://git.openjdk.org/jdk/pull/14321/files/5fd8a047..7c629490

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14321&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14321&range=01-02

  Stats: 1545 lines in 54 files changed: 1081 ins; 170 del; 294 mod
  Patch: https://git.openjdk.org/jdk/pull/14321.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14321/head:pull/14321

PR: https://git.openjdk.org/jdk/pull/14321