[Extensions] AlternateStyle property

[Avid29]

Fixes #767 #769

PR Type

What kind of change does this PR introduce?

Extends the existing API for ListViewExtensions and lightly adjusts the event subscription/handling behavior

What is the current behavior?

Currently, only the background color of an alternate row is adjustable.

Also, event subscriptions are handled separately for each AlternateRow attached property.

What is the new behavior?

Now the Style of alternate row elements are adjustable using the AlternateStyle attached property.

Additionally, the handling and subscriptions to events have been grouped into one event adjusting as appropriate for each set property.

PR Checklist

Please check if your PR fulfills the following requirements:

• Created a feature/dev branch in your fork (vs. submitting directly from a commit on main)
• Based off latest main branch of toolkit
• Tested code with current supported SDKs
• New component
  • Documentation has been added
  • Sample in sample app has been added
  • Analyzers are passing for documentation and samples
  • Icon has been created (if new sample) following the Thumbnail Style Guide and templates
• Tests for the changes have been added (if applicable)
• Header has been added to all new source files
• Contains NO breaking changes

Other information

[Avid29]

NOTE: This PR is based on #763 and should remain a draft until that PR is merged