SqlAGReplica: Run Update-AvailabilityGroupReplica Once for All AvailabilityReplica Changes

[hollanjs]

Pull Request (PR) description

This PR alters how the SqlAGReplica changes properties of the AvailabilityReplica. Rather than triggering an update for each individual property that is out of state, Update-AvailabilityGroupReplica now triggers only once at the end, applying all property updates at once.

To specifically resolve issues with FailoverMode and AvailabilityMode updates:

• FailoverMode checks were moved up before AvailabilityMode checks
• An additional tests has been added specifically to ensure FailoverMode and AvailabilityMode are always updated at the same time. This should hopefully ensure future changes do not cause this issue to come back.

This Pull Request (PR) fixes the following issues

• Fixes #1817

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 #1840 (d59a357) into main (979800d) will increase coverage by 0%. The diff coverage is 100%.

@@         Coverage Diff          @@
##           main   #1840   +/-   ##
====================================
  Coverage    91%     91%           
====================================
  Files        71      71           
  Lines      7310    7313    +3     
====================================
+ Hits       6661    6664    +3     
  Misses      649     649           

Flag	Coverage Δ
unit	91% <100%> (+<1%)	:arrow_up:

Impacted Files	Coverage Δ
...SCResources/DSC_SqlAGReplica/DSC_SqlAGReplica.psm1	100% <100%> (ø)

[johlju]

@hollanjs awesome work! Looks great at initial glance. Will review later today.