RFR: 8336942: Improve test coverage for class loading elements with annotations of different retentions [v3]

[Liam Miller-Cushon]

> This changes adds some additional test coverage for the handling of type use annotations read from class files added in [JDK-8225377](https://bugs.openjdk.org/browse/JDK-8225377).
> 
> If both a `RUNTIME` and `CLASS` retention type annotation appear on the same element loaded from a class file, the annotations are attached by separate `TypeAnnotationCompleter's`s, and the logic in `ClassReader` needs to merge the annotations from the second attribute with annotations added by the first one.
> 
> The implementation already handles this correctly, but there isn't explicit test coverage for it. This change adds test coverage for that case.

Liam Miller-Cushon 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:

 - Merge branch 'master' into JDK-8336942
 - Merge branch 'master' into JDK-8336942
 - Sort entries in nameToAnnotation
 - 8336942: Improve test coverage for class loading elements with annotations of different retentions

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/20287/files
  - new: https://git.openjdk.org/jdk/pull/20287/files/7e5bbd58..d44ee835

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20287&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20287&range=01-02

  Stats: 48462 lines in 1406 files changed: 30418 ins; 10621 del; 7423 mod
  Patch: https://git.openjdk.org/jdk/pull/20287.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20287/head:pull/20287

PR: https://git.openjdk.org/jdk/pull/20287