Add 'BasicScrollingConsole' to support test cases for scrolling up scenarios

[daxian-dbw]

PR Summary

The major changes included are:

1. Add BasicScrollingConsole along with other testing infrastructure improvements to support tests cases for scrolling up scenarios.
2. Add test cases to cover some fixes to bugs related to scrolling up scenarios:
   • Tab autocomplete in a Cmdlet param context #2928
   • Menu completion doesn't work properly when scrolling happens #2948
   • Dynamic help rendering behaves incorrectly when buffer scrolling is required #2950
3. Fixed another scrolling up issue in menu completion, which I discovered while working on the tests.

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
• 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

[daxian-dbw]

@andschwa Can you please do a review for me? Thanks!

[andyleejordan]

Some very extension test updates and a good edge case fix, I like it!

[ghost]

🎉 v2.2.0-beta5 has been released which incorporates this pull request. 🎉