xRDRemoteApp strip common parameters in Test-TargetResource

[danielboth]

Pull Request (PR) description

This PR fixes an issue where (for example) Verbose is passed to Test-TargetResource in xRDRemoteApp, which will then be compared vs the current configuration.

This Pull Request (PR) fixes the following issues

• Fixes #69

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).
• [ ] 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.
• [ ] 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[bot]]

Codecov Report

Merging #70 into master will increase coverage by 0.06%. The diff coverage is 88.88%.

@@            Coverage Diff             @@
##           master      #70      +/-   ##
==========================================
+ Coverage    87.4%   87.46%   +0.06%     
==========================================
  Files           8        8              
  Lines         381      383       +2     
  Branches        9        9              
==========================================
+ Hits          333      335       +2     
  Misses         39       39              
  Partials        9        9

Impacted Files	Coverage Δ
...Resources/MSFT_xRDRemoteApp/MSFT_xRDRemoteApp.psm1	97.87% <100%> (+0.09%)	:arrow_up:
...RDSessionDeployment/MSFT_xRDSessionDeployment.psm1	94.73% <83.33%> (ø)	:arrow_up:

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