Improve sample app UI

[AndrewKeepCoding]

Improved and fixed some issues on the sample app.

[dotMorten]

I'm at Build right now so can't test it but what is this specifically addressing?

[AndrewKeepCoding]

Just improved a couple of margin settings and fixed the Settings page title from "Windows Design" to "Settings". Nothing critical.

[dotMorten]

Maybe I'm just not clear on what was wrong with them in the first place? Also not sure I get the rename to settings - winuiex doesn't have any settings apis

[AndrewKeepCoding]

For example, in the Windows Control page, the buttons have inconsistent look and spacing. One of them not showing its entire content: This is how it looks after the change:

[AndrewKeepCoding]

I also fixed the Settings page title: to:

[AndrewKeepCoding]

This PR has become old. Closing it.