* Added the module `border`
* Added `BorderStyle` and `CalculatedBorder` types.
* Added `border_style` and `calculated_border` fields to `NodeBundle` and `ButtonBundle`
* Added the `extract_uinode_borders` system to the UI Render App.
* Added the `calculate_borders_system` which calculates the border geometry for each node.
* Added the UI example `borders`
* Changed the button example to give the button a border.

* Changed `calculate_borders_system` to remove the previous border geometry of degnerate nodes before continuing.

…ers in `calculate_borders_system`

…nction

* moved `compute_matrix` out of loop
* added comments to border module
* removed border overflow clamping

* Renamed `BorderStyle` to `BorderColor` and made it a tuple-struct.
* Added `BorderBundle` which contains the components needed by a node to draw a border.
* Renamed the `border_style` fields of `NodeBundle` and `ButtonBundle` to `border_color`.

* Removed the `borders` module.
* Removed the `CalculatedBorder` type.
* Removed the `calculate_borders_system
* Moved the border rect calculations into `extract_uinode_borders`.

…`.min`

Co-authored-by: Nico Burns <nico@nicoburns.com>

* fixed viewport size calculation in `extract_uinode_borders`
* added `viewport_debug` example

* To calculate the logical size of the viewport for viewport coordinates, the physical size of the window shouldn't be multipied by the `UiScale` only the window's scale factor.
* Use the viewport width to determine the border thickness for root UI nodes with percentage border values.

…ed from parent width.

… `height`

…orderColor`.

…nner loop.