Experimental wgpu WebGL backend support

- Added missing `draw_cache_align_4x4` call for `brush_glyph` on wasm32 target
- Added WebGL support to `integratio_wgpu` example
- Fixed test.yml CI workflow
- Removed spir-v shader in `integration_wgpu`; Fixed formatting
- Removed redundant `BoxStream` typedef

winit/Cargo.toml

@@ -14,7 +14,6 @@ categories = ["gui"]
 debug = ["iced_native/debug"]
 
 [dependencies]
-window_clipboard = "0.2"
 log = "0.4"
 thiserror = "1.0"
 
@@ -37,3 +36,6 @@ path = "../futures"
 
 [target.'cfg(target_os = "windows")'.dependencies.winapi]
 version = "0.3.6"
+
+[target.'cfg(not(target_arch = "wasm32"))'.dependencies.window_clipboard]
+version = "0.2"