PR Summary

Reviewed the APIs being used. Get-Counter can work with just public APIs published in pdh.h. Import-Counter and Export-Counter rely on undocumented APIs so those are removed. The PDH apis are really old so I don't believe there's any chance to get those APIs or the binary log format documented so removed that code. Get-Counter -ListSet has Description property as empty because it isn't supported by PDH apis.

PR Checklist

• PR has a meaningful title
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• Summarized changes
• Make sure all .h, .cpp, .cs, .ps1 and .psm1 files have the correct copyright header
• This PR is ready to merge and is not Work in Progress.
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• Breaking changes
  • None
  • OR
  • Experimental feature(s) needed
    • Experimental feature name(s):
• User-facing changes
  • Not Applicable
  • OR
  • Documentation needed
    • Issue filed: Bring back doc for Get-Counter cmdlet for PS7 MicrosoftDocs/PowerShell-Docs#5020
• Testing - New and feature
  • N/A or can only be tested interactively
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  • Make sure you've added a new test if existing tests do not effectively test the code changed
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    • Impact on PowerShell Editor Services which is used in the PowerShell extension for VSCode (which runs in a different PS Host).
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