Align ContentControl Behavior with UWP behavior for empty children.

[Iguins]

GitHub Issue (If applicable): #

PR Type

What kind of change does this PR introduce?

What is the current behavior?

When a ContentControl in the Visual Tree does not have child elements, the dataContext is displayed instead of nothing like on UWP

What is the new behavior?

Now when a ContentControl does not have content, the control will be empty.

PR Checklist

Please check if your PR fulfills the following requirements:

• Tested code with current supported SDKs
• Docs have been added/updated which fit documentation template (for bug fixes / features)
• Unit Tests and/or UI Tests for the changes have been added (for bug fixes / features) (if applicable)
• Wasm UI Tests are not showing unexpected any differences. Validate PR Screenshots Compare Test Run results.
• Contains NO breaking changes
• Updated the Release Notes
• Associated with an issue (GitHub or internal)

Other information

Internal Issue (If applicable):

[MatFillion]

We should build a few tests for this :)

[Iguins]

We should build a few tests for this :)

Incoming, trying to make relevant tests :)