`Get-SqlDscPreferredModule`: New command

[johlju]

Pull Request (PR) description

• SqlServerDsc
  • New public command:
  • Get-SqlDscPreferredModule - Returns the name of the first available preferred module (issue #1879).
• Import-SqlDscPreferredModule
  • Refactor to re-use the command Get-SqlDscPreferredModule.

This Pull Request (PR) fixes the following issues

• Fixes #1879

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.
• [x] Comment-based help updated, including parameter descriptions.
• [x] Localization strings updated.
• [ ] Examples updated.
• [x] 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 #1898 (a429225) into main (4602416) will increase coverage by 0%. The diff coverage is 100%.

@@         Coverage Diff          @@
##           main   #1898   +/-   ##
====================================
  Coverage    92%     92%           
====================================
  Files        85      86    +1     
  Lines      7647    7661   +14     
====================================
+ Hits       7045    7059   +14     
  Misses      602     602           

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

Impacted Files	Coverage Δ
source/Public/Get-SqlDscPreferredModule.ps1	100% <100%> (ø)
source/Public/Import-SqlDscPreferredModule.ps1	100% <100%> (ø)