RFR: 8357995: Use "stdin.encoding" for reading System.in with InputStreamReader/Scanner [core] [v7]

[Volkan Yazici]

> Passes the `Charset` read from the `stdin.encoding` system property while creating `InputStreamReader` or `Scanner` instances for `System.in`.
> 
> `stdin.encoding` is a recently added property for Java 25 in [JDK-8350703](https://bugs.openjdk.org/browse/JDK-8350703). Employing it throughout the entire code base is addressed by the parent ticket [JDK-8356893](https://bugs.openjdk.org/browse/JDK-8356893). JDK-8357995 this PR is addressing is a sub-task of JDK-8356893 and is concerned with only areas related to core libraries.

Volkan Yazici has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 14 commits:

 - Merge remote-tracking branch 'upstream/master' into stdinEnc-core
 - Revert superfluous test changes
 - Improve code style
   
   Co-authored-by: Andrey Turbanov <turbanoff at gmail.com>
 - Fix missing `java.io.Reader` import in `Ktab`
 - Clean-up `MultiBreakpointsTarg`
 - Provide fallback for `stdin.encoding`
 - Revert changes to `Application` and `JavaChild`
   
   There stdin is connected to the parent process rather than the console.
 - Revert more superfluous changes
 - Fix code typo
 - Discard changes unrelated with core libraries
 - ... and 4 more: https://git.openjdk.org/jdk/compare/9aeacf2d...d36e0bd5

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Changes: https://git.openjdk.org/jdk/pull/25544/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25544&range=06
  Stats: 130 lines in 11 files changed: 33 ins; 28 del; 69 mod
  Patch: https://git.openjdk.org/jdk/pull/25544.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25544/head:pull/25544

PR: https://git.openjdk.org/jdk/pull/25544