DiskAccessPath Add Disk Subsystem Refresh before set - Fixes #121

[PlagueHO]

Pull Request (PR) description

• DiskAccessPath:
  • Added function to force refresh of disk subsystem at the start of Set-TargetResource to prevent errors occuring when the disk access path is already assigned - See Issue 121

This PR also supercedes #152, #126

This Pull Request (PR) fixes the following issues

• Fixes #121

Task list

• [x] Added an entry under the Unreleased section of the change log in the CHANGELOG.md. Entry should say what was changed, and how that affects users (if applicable).
• [ ] Resource documentation added/updated in README.md in the resource folder.
• [ ] Resource parameter descriptions added/updated in 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 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.

@johlju - would you mind reviewing this when you get a chance?

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This change is 

[codecov-io]

Codecov Report

Merging #209 into dev will increase coverage by <1%. The diff coverage is 100%.

@@         Coverage Diff         @@
##           dev   #209    +/-   ##
===================================
+ Coverage   95%    95%   +<1%     
===================================
  Files        7      7            
  Lines      958    978    +20     
===================================
+ Hits       917    937    +20     
  Misses      41     41

[PlagueHO]

Thanks @johlju !!!