Tab Bar View can hide separator and disable blur effect

[cbowdoin]

Platforms Impacted

• iOS
• visionOS
• macOS

Description of changes

Consumers have no way currently to control the separator and blur effect created by the tab bar view. This PR adds the ability to specify in the init that you want to disable either/both the separator or the blur effect. We do not apply any effect to the background view if the blur effect is disabled. If the separator is disabled we will set the hidden property on the separator view to true.

Tab Bar View demo app has the incrementor on the right and decrementor on the left to match LTR design patterns.
Additionally, it now has toggles for the control of the separator and blur effect.

Binary change

(how is our binary size impacted -- see https://github.com/microsoft/fluentui-apple/wiki/Size-Comparison)

Verification

• Built objective c projects that use Tab Bar View
• Tab Bar View can be seen with no separator and blur effect in the demo controller.

Visual Verification

Before	After

Pull request checklist

This PR has considered:

• Light and Dark appearances
• iOS supported versions (all major versions greater than or equal current target deployment version)
• VoiceOver and Keyboard Accessibility
• Internationalization and Right to Left layouts
• Different resolutions (1x, 2x, 3x)
• Size classes and window sizes (iPhone vs iPad, notched devices, multitasking, different window sizes, etc)
• iPad Pointer interaction
• SwiftUI consumption (validation or new demo scenarios needed)
• Objective-C exposure (provide it only if needed)

Microsoft Reviewers: Open in CodeFlow

[nodes11]

A video demonstrating the updates to the demo controller should be added to the visual verification section.

[anandrajeswaran]

Random thought - do we ever expect someone to toggle one of these but not both of these? If not, could encapsulate into single declarative property that effectively saws "are you detaching a tab bar from its child view controller"?