Remove unnecessary allocations from custom shaders

While this new approach made the single-function drawing operations a
thing of the past, this new approach allows for implementing the example
without the option-initialize flow, and it supports the ability for
custom drawing operations to take parameters and pass information
through to the render phase.

CHANGELOG.md

@@ -278,9 +278,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   outlines drawn in the user interface.
 - `FocusColor` is a new component that controls the color of the keyboard focus
   indicator.
-- `Graphics::draw` is a new function that allows performing arbitrary `wgpu`
-  drawing operations when rendering. See the `shaders.rs` example for an example
-  on how to use this to render into a Canvas with a custom shader.
+- `Graphics::draw` and `Graphics::draw_with` are a new function that allows
+  performing arbitrary `wgpu` drawing operations when rendering. See the
+  `shaders.rs` example for an example on how to use this to render into a Canvas
+  with a custom shader.
 
 
 [139]: https://github.com/khonsulabs/cushy/issues/139