RFR: JDK-8273146: Start of release updates for JDK 19 [v6]

[Joe Darcy]

> The time to get JDK 19 underway draws nigh, please review this usual set of start-of-release updates, including CSRs for the javac and javax.lang.model updates:
> 
> JDK-8277512: Add SourceVersion.RELEASE_19
> https://bugs.openjdk.java.net/browse/JDK-8277512
> 
> JDK-8277514: Add source 19 and target 19 to javac
> https://bugs.openjdk.java.net/browse/JDK-8277514
> 
> Clean local tier 1 test runs for langtools, jdk, and hotspot.

Joe Darcy has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains ten commits:

 - Merge branch 'master' into JDK-8273146
 - Update symbol information for JDK 18 b25.
 - Merge branch 'master' into JDK-8273146
 - Merge branch 'master' into JDK-8273146
 - Remove SharedSpaces options from VMDeprecatedOptions.java.
 - Merge branch 'master' into JDK-8273146
 - Respond to review feedback.
 - Add --release 18 information. Good tier1 test results.
 - JDK-8273146: Start of release updates for JDK 19

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Changes: https://git.openjdk.java.net/jdk/pull/6493/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6493&range=05
  Stats: 3286 lines in 68 files changed: 3242 ins; 4 del; 40 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6493.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6493/head:pull/6493

PR: https://git.openjdk.java.net/jdk/pull/6493