Expose properties now that Views can be queried.

[museun]

Views that implement builder and could have public properties:

• Aligned
• Background
• Button
• Checkbox
• Constrain
• Expander
• Fill
• Flexible
• Frame
• KeyArea
• Label
• List
• MouseArea
• Offset
• Padding
• Progress
• Radio
• Selected
• Separator
• Slider
• TextInput
• TodoValue
• Toggle
• ToggleSwitch
• Unconstrained
• Wrap

[museun]

Should the ApplicableStyle<S: Style> be considered a property?

How would we even name the S type where its dyn-compatible (for Erased.)

Technically because the user gives the 'v, B: Builder<'v, View = V> we could return some erased Style type and then cast that to the B::Style because we can have type ids here without storing/using them in the View -> Erased stuff.

The erased style thing would need

• as_concrete_style<B: Builder>() -> Option<&B::Style>
• as_concrete_style_mut<V: Builder>() -> Option<&mut B::Style>

at the very least. But have that generic there would not be dyn-safe. So we'd have to do yet another erased (maybe a Box<dyn Fn()> that erases the as_concrete_style() into a closure where we capture a TypeId. But this is even more annoying.