RFR: 8372004: Have SSLLogger implement System.Logger

[Sean Coffey]

`SSLLogger` utilizes `System.Logger` if the `javax.net.debug` system property key value is empty. However, since that class doesn't implement `SSLogger`, it misses the advantage of highlighting the exact calling site for each log statement.  Having `SSLLogger `simply implement `System.Logger` fixes this

I've also taken this opportunity to refractor the `isOn` boolean in `SSLLogger`. Encapsulated that boolean in a new method which callers can now use. I also used `ForceInline` directory on that method. Thanks to @dfuch for suggestions on that front.

Also updated an existing unit testcase to test for the new functionality

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Commit messages:
 - 8372004

Changes: https://git.openjdk.org/jdk/pull/28376/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28376&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8372004
  Stats: 827 lines in 80 files changed: 43 ins; 42 del; 742 mod
  Patch: https://git.openjdk.org/jdk/pull/28376.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28376/head:pull/28376

PR: https://git.openjdk.org/jdk/pull/28376