egui-wgpu renderer renaming (#2021)

- `RenderPass` -> `Renderer`
- `RenderPass::execute` -> `Renderer::render`
- `RenderPass::execute_with_renderpass` -> `Renderer::render_onto_renderpass`
- reexport `Renderer` in `lib.rs`

crates/egui-wgpu/src/lib.rs

@@ -11,6 +11,7 @@ pub use wgpu;
 /// Low-level painting of [`egui`] on [`wgpu`].
 pub mod renderer;
 pub use renderer::CallbackFn;
+pub use renderer::Renderer;
 
 /// Module for painting [`egui`] with [`wgpu`] on [`winit`].
 #[cfg(feature = "winit")]