(microsoft-ui-xaml) Update WinUI to version 2.8.6

[huynhsontung]

Requirements

• I have read the CONTRIBUTING.md.
• My changes confirm to what is requested in CONTRIBUTING.md.

Description

Rename microsoft-ui-xaml - 2.8 to microsoft-ui-xaml-2-8, similar to microsoft-ui-xaml-2-7. Update the appx packages from 2.8.4 to 2.8.6.

Motivation and Context

There is a microsoft-ui-xaml-2-7 package but no microsoft-ui-xaml-2-8 package. The latest WinUI package should be 2.8.

How Has this Been Tested?

Screenshot (if appropriate, usually isn't needed):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this repository (if your change does not follow the style it will likely be rejected - this includes changes in formatting / layout).
• My change requires a change to the documentation (this usually means the notes in the description of a package) and I have updated the documentation accordingly.
• I have updated the package description and it is less than 4000 characters.
• The added / modified package passed install / uninstall in the chocolatey test environment.
• The changes only affect a single package (not including meta package).