Support disabling touches via allowsHitTesting

[bryankeller]

Details

This PR enables folks to disable user interaction on SwiftUI views by using the allowsHitTesting modifier.

Related Issue

#291

Motivation and Context

Fix issues (we also ran into this at Airbnb recently when trying to disable certain days from being tappable)

How Has This Been Tested

Example app

Types of changes

• Docs change / refactoring / dependency upgrade
• 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 project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.