ActiveDirectoryDsc: Add stubs generated by Indented.StubCommand

[johlju]

Pull Request (PR) description

• Changes to ActiveDirectoryDsc
  • Added new stubs for the cmdlets and classes to be used with unit tests.
    The new stubs are based on the modules ActiveDirectory and ADDSDeployment
    in Windows Server 2019. The stubs are generated using the PowerShell
    module Indented.StubCommand. Instructions how to generate stubs
    (for example for a new operating system) has been added to the README.md
    in the Tests/Unit/Stubs folder (issue #245).
  • Update all unit tests removing all local stub functions in favor of
    the new stub modules.
  • Changes to ActiveDirectoryDsc.Common.
    • Updated the function Test-ADReplicationSite to make the parameter
      Credential mandatory.

This Pull Request (PR) fixes the following issues

• Fixes ActiveDirectoryDsc: Add stubs to be used with unit tests #245

Task list

• Added an entry under the Unreleased section in the CHANGELOG.md.
  Entry should say what was changed, and how that affects users (if applicable).
• Resource documentation added/updated in resource directory README.md.
• Resource parameter descriptions added/updated in schema.mof
  and comment-based help.
• Comment-based help added/updated.
• Conceptual help topic added/updated (cultureFolder\about_ResourceName.help.txt).
• Localization strings added/updated in all localization files as appropriate.
• Examples appropriately added/updated.
• Unit tests added/updated. See DSC Resource Testing Guidelines.
• Integration tests added/updated (where possible). See DSC Resource Testing Guidelines.
• New/changed code adheres to DSC Resource Style Guidelines and Best Practices.

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This change is 

[codecov-io]

Codecov Report

Merging #483 into dev will not change coverage.
The diff coverage is n/a.

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  Misses       32     32           
  Partials     10     10

[johlju]

Waiting for the proposed PR indented-automation/Indented.StubCommand#21 to be merged since that is a prerequisites for this change.

[johlju]

Reviewed 28 of 28 files at r1.
Reviewable status: complete! all files reviewed, all discussions resolved