v1: Rename `ConstrainedControl` to `LayoutControl`, swap `Button` and `ElevatedButton`

* Rename `ConstrainedControl` to `LayoutControl`, mark `ConstrainedControl` as deprecated with removal in Flet 1.0.
* Move properties and methods from `ElevatedButton` to `Button`, mark `ElevatedButton` as deprecated with removal in Flet 1.0.