RFR: 8343598: Since Checker can mark some preview elements as new even if bytecode reference is identical

[Nizar Benalla]

Can I get a review for this test only change to the Since Checker?

I drop the distinction between classes and interfaces when generating ids and use a generic name "class" to describe both, as to not consider classes that get converted to interfaces (and vice versa) as new API (Something that may happen to APIs in preview).

TIA.

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

Commit messages:
 - drop uses of "interface:"

Changes: https://git.openjdk.org/jdk/pull/22213/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22213&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8343598
  Stats: 12 lines in 1 file changed: 0 ins; 4 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/22213.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22213/head:pull/22213

PR: https://git.openjdk.org/jdk/pull/22213