Add WDAC events and system lockdown notification

[PaulHigin]

PR Summary

This PR adds new ETW events for WDAC calls, and also a start-up notification when the system is in lock down and PowerShell console runs in Constrained Language mode.

#18628

PR Context

WDAC (Windows Defender Application Control) is a Windows OS application control policy, and PowerShell complies with the system policy through added restrictions and language modes. This PR adds ETW event logging for calls PowerShell makes to WDAC in order to determine if the system is in lock down mode, and if a script file is allowed by the WDAC policy. It also adds to the PowerShell start-up banner a notification if the console is starting in Constrained Language mode due to WDAC policy.

PR Checklist

• PR has a meaningful title
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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:
• Testing - New and feature
  • N/A or can only be tested interactively
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• Tooling
  • I have considered the user experience from a tooling perspective and don't believe tooling will be impacted.
  • OR
  • I have considered the user experience from a tooling perspective and opened an issue in the relevant tool repository. This may include:
    • Impact on PowerShell Editor Services which is used in the PowerShell extension for VSCode
      (which runs in a different PS Host).
      • Issue filed:
    • Impact on Completions (both in the console and in editors) - one of PowerShell's most powerful features.
      • Issue filed:
    • Impact on PSScriptAnalyzer (which provides linting & formatting in the editor extensions).
      • Issue filed:
    • Impact on EditorSyntax (which provides syntax highlighting with in VSCode, GitHub, and many other editors).
      • Issue filed:

[pull-request-quantifier-deprecated]

This PR has 83 quantified lines of changes. In general, a change size of upto 200 lines is ideal for the best PR experience!

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Quantification details

Label      : Small
Size       : +70 -13
Percentile : 33.2%

Total files changed: 9

Change summary by file extension:
.cs : +61 -13
.resx : +9 -0

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[ghost]

🎉v7.4.0-preview.2 has been released which incorporates this pull request.:tada:

Handy links:

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