`Install-SqlDscServer`: Fix `ASSysAdminAccounts` and `SqlSysAdminAccounts`

[johlju]

Pull Request (PR) description

• Assert-SetupActionProperties
  • Now throws an exception if the setup action is Install and the feature analysis services is specified without the parameter ASSysAdminAccounts (issue #1845).
  • Now throws an exception if the setup action is Install and the feature database engine is specified without the parameter SqlSysAdminAccounts.
• Invoke-SetupAction
  • The parameter SqlSysAdminAccounts is no longer mandatory to allow installation where the database engine is not installed.
• Install-SqlDscServer
  • The parameter SqlSysAdminAccounts is no longer mandatory to allow installation where the database engine is not installed.

This Pull Request (PR) fixes the following issues

• Fixes #1845

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.
• [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 #1863 (d8b4465) into main (58b765c) will increase coverage by 0%. The diff coverage is 100%.

@@         Coverage Diff          @@
##           main   #1863   +/-   ##
====================================
  Coverage    92%     92%           
====================================
  Files        85      85           
  Lines      7607    7614    +7     
====================================
+ Hits       7005    7012    +7     
  Misses      602     602           

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

Impacted Files	Coverage Δ
source/Private/Invoke-SetupAction.ps1	92% <ø> (ø)
source/Public/Install-SqlDscServer.ps1	100% <ø> (ø)
source/Private/Assert-SetupActionProperties.ps1	98% <100%> (+<1%)	:arrow_up: