SqlServerPermission: Added support for assigning permissions to a server role.

[IAMJDA]

Pull Request (PR) description

Updated Set-SqlDscServerPermission to be able to set permission on server roles. Adapted unit tests so they should continue to work but missing support for the new logic.

This Pull Request (PR) fixes the following issues

• Fixes Set-SqlDscServerPermission: Not possible to set server permissions for a server role #2059

Task list

• 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.
• Code changes adheres to DSC Community Style Guidelines.

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This change is 

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93%. Comparing base (85ea1ed) to head (57aecc3).

Additional details and impacted files

@@          Coverage Diff           @@
##           main   #2061     +/-   ##
======================================
- Coverage    94%     93%     -1%     
======================================
  Files        94      36     -58     
  Lines      7930    6341   -1589     
======================================
- Hits       7500    5953   -1547     
+ Misses      430     388     -42     

Flag	Coverage Δ
unit	93% <ø> (-1%)	⬇️

see 58 files with indirect coverage changes