Fix copying text to system clipboard on Linux using xclip

[daxian-dbw]

PR Summary

Fix #1993
Fix #3884

Fix copying text to system clipboard on Linux using xclip.
Avoid reading the standard output pipe when it's not needed to do so. So, we redirect but don't read the stdout when setting text to clipboard using xclip, and only read the output when we are getting text from the clipboard.

PR Checklist

• PR has a meaningful title
  • Use the present tense and imperative mood when describing your changes
• Summarized changes
• Make sure you've added one or more new tests only able to test manually
• Make sure you've tested these changes in terminals that PowerShell is commonly used in (i.e. conhost.exe, Windows Terminal, Visual Studio Code Integrated Terminal, etc.)
• User-facing changes
  • Not Applicable
  • OR
  • Documentation needed at PowerShell-Docs
    • Doc Issue filed:

Microsoft Reviewers: Open in CodeFlow

[andyleejordan]

Nice!