Fixed Segment hover part CornerRadius

[Avid29]

Fixes #716

PR Type

What kind of change does this PR introduce?

Bugfix

What is the current behavior?

In the default style, regardless of the SegmentItem.CornerRadius, the PART_Hover.CornerRadius will be 2.

What is the new behavior?

In the default style, PART_Hover.CornerRadius will be the value assigned to SegmentItem.CornerRadius.

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
• Contains NO breaking changes

The default style behavior is minorly different. Might result in undesired visuals in rare cases.

Other information

I suppose this is better behavior for the default style. However in reality, I think the answer to #716 is that if you want to modify the CornerRadius of a SegmentedItem and really make it look good, you need to write your own Style and ControlTemplate

[HEIC-to-JPEG-Dev]

Yes, the new design is the expected behavior. No underlying knowledge of the control should be required and creating a new style and controlTemplate is a not expected. Why have a property if, when you set it, someone tells you "oh, to make that work properly you have to write a style and controlTemplate" - yeah, bye bye - remove the property if it doesn't work, or keep it and make it work :)

[Avid29]

@HEIC-to-JPEG-Dev I only say you may have to write your own style, because frankly I don't love how this looks 😂. Don't really know how to improve it though...
I believe the CornerRadius property is inherited and cannot be removed.

[michael-hawker]

FYI @niels9001 think this is good, eh?