`Invoke-SetupAction`: Expand environment variables

[johlju]

Pull Request (PR) description

• Update private command:
  • Invoke-SetupAction was changed to expand environment variables that is passed as the media path.

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 updated in the resource's README.md.
• [ ] Resource parameter descriptions updated in schema.mof.
• [ ] Comment-based help updated, including parameter descriptions.
• [ ] Localization strings updated.
• [ ] Examples updated.
• [ ] Unit tests updated. See DSC Community Testing Guidelines.
• [ ] Integration tests updated (where possible). See DSC Community Testing Guidelines.
• [x] Code changes adheres to DSC Community Style Guidelines.

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This change is 

[codecov[bot]]

Codecov Report

Merging #1914 (da54ca6) into main (d8e6b74) will increase coverage by 0%. The diff coverage is 100%.

@@         Coverage Diff          @@
##           main   #1914   +/-   ##
====================================
  Coverage    92%     92%           
====================================
  Files        91      91           
  Lines      7714    7715    +1     
====================================
+ Hits       7111    7112    +1     
  Misses      603     603           

Flag	Coverage Δ
unit	92% <100%> (+<1%)	:arrow_up:

Impacted Files	Coverage Δ
source/Private/Invoke-SetupAction.ps1	92% <100%> (+<1%)	:arrow_up: