ActiveDirectoryDsc: Migrate HQRM And Unit Tests to PowerShell 7

[X-Guardian]

Pull Request (PR) description

This PR migrates the HQRM and Unit Tests to using PowerShell 7 in the CI. This is to avoid this PowerShell performance issue with Pester: https://github.com/pester/Pester/issues/1318. This reduces the runtime of the Unit Tests in the CI from 45 minutes to 10 minutes.

Changes that had to be made as part of this:

• New function Get-ByteContent used by the ADUser resource Get-ThumbnailByteArray function to cope with different Get-Content parameters between PowerShell Desktop and Core.
• Compare-ResourcePropertyState test changes to handle differences between PowerShell Desktop And Core with hashtable ordering.
• ActiveDirectory stub module changes due to PowerShell Core unimplemented SecurityIdentifier property of the System.Security.Principal class.
• Implementation of a stub module for Kds as this module will not currently import on PowerShell Core.

This Pull Request (PR) fixes the following issues

None

Task list

• [x] Added an entry to the change log under the Unreleased section of the file CHANGELOG.md. Entry should say what was changed and how that affects users (if applicable), and reference the issue being resolved (if applicable).
• [ ] Resource documentation added/updated in README.md.
• [ ] Resource parameter descriptions added/updated in README.md, schema.mof and comment-based help.
• [ ] Comment-based help added/updated.
• [ ] Localization strings added/updated in all localization files as appropriate.
• [ ] Examples appropriately added/updated.
• [x] Unit tests added/updated. See DSC Community Testing Guidelines.
• [ ] Integration tests added/updated (where possible). See DSC Community Testing Guidelines.
• [x] New/changed code adheres to DSC Community Style Guidelines.

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This change is 

[johlju]

@X-Guardian Awesome work! 😄