xRDCertificateConfiguration: New resource to enable certificate management

[danielboth]

Pull Request (PR) description

New resource to enable the management of the certificates in a remote desktop deployment. This resource enables the configuration of each role individually, so users can have different certificates between roles.

This Pull Request (PR) fixes the following issues

• Fixes #63

Task list

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

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This change is 

[codecov-io]

Codecov Report

Merging #67 into dev will increase coverage by 0.65%. The diff coverage is 93.87%.

@@            Coverage Diff            @@
##             dev      #67      +/-   ##
=========================================
+ Coverage   87.4%   88.05%   +0.65%     
=========================================
  Files          8        9       +1     
  Lines        381      427      +46     
  Branches       9       10       +1     
=========================================
+ Hits         333      376      +43     
- Misses        39       41       +2     
- Partials       9       10       +1

Impacted Files	Coverage Δ
xRemoteDesktopSessionHostCommon.psm1	86.66% <84.61%> (-13.34%)	:arrow_down:
...onfiguration/MSFT_xRDCertificateConfiguration.psm1	97.22% <97.22%> (ø)
...RDSessionDeployment/MSFT_xRDSessionDeployment.psm1	94.73% <0%> (ø)	:arrow_up:

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[danielboth]

Hi @johlju, would you have some time to review?

[danielboth]

This PR was moved to: https://github.com/dsccommunity/xRemoteDesktopSessionHost/pull/75