ADDITIONAL SYSTEM INFORMATION :
openjdk 21.0.3 2024-04-16 LTS
OpenJDK Runtime Environment Temurin-21.0.3+9 (build 21.0.3+9-LTS)
OpenJDK 64-Bit Server VM Temurin-21.0.3+9 (build 21.0.3+9-LTS, mixed mode, sharing)

Windows 24H2

I read https://docs.oracle.com/en/java/javase/24/docs/api/java.base/java/io/Console.html and confirmed such a method doesn't exist in Java 24.

A DESCRIPTION OF THE PROBLEM :
There are some environments where the encodings of stdin and stdout are different (especially in Windows).

```pwsh
[Console]::OutputEncoding = [System.Text.Encoding]::UTF8
[Console]::InputEncoding = [System.Text.Encoding]::GetEncoding(437)
```

In such environments, you have to verbosely write`Charset.forName(System.getProperty("stdin.encoding"))` instead of the simple `System.console().charset()`.
Now that we have stdin.encoding property today (JDK-8355357), we should have this `inputCharset()` method, too. It is just `stdin.encoding` - `stdout.encoding` + `charset()`.