RFR: JDK-8322878: Including sealing information Class.toGenericString() [v4]

[Joe Darcy]

> As recently discussed on core libs, sealed-ness information could be included in the Class.toGenericString() output, analagous to how "modifiers" that also correspond to JVM access flags are handled.
> 
> This is the initial spec, implementation, and test updated needed for that change. If there is consensus this is a reasonable direction, I'll create the CSR, etc.

Joe Darcy has updated the pull request incrementally with one additional commit since the last revision:

  Improve regression test.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/17239/files
  - new: https://git.openjdk.org/jdk/pull/17239/files/ac897d9b..e1efbf30

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17239&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17239&range=02-03

  Stats: 24 lines in 1 file changed: 9 ins; 0 del; 15 mod
  Patch: https://git.openjdk.org/jdk/pull/17239.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17239/head:pull/17239

PR: https://git.openjdk.org/jdk/pull/17239