ShellStream: Buffer is not flushed before read

[drieseng]

When one of the Read(Line) or Expect overloads is invoked, the write buffer should first be flushed.

[IgorMilavec]

I have created a discussion #926 for all ShellStream related issues.

[WojciechNagorski]

This issue has been fixed in the 2024.0.0 version.