[wgpu] Expose wgpu::Adapter via RenderState (#2954)

* [wgpu] Expose adapter, better errors, better docs, more code sharing, use stencil bits

* doc fix

* remove unnecessary unsafe

* handle missing framebuffer format

* better handling of renderstate creation in winit.rs

* remove unnecessary use directive

Cargo.toml

@@ -33,3 +33,6 @@ opt-level = 2 # fast and small wasm, basically same as `opt-level = 's'`
 # Optimize all dependencies even in debug builds (does not affect workspace packages):
 [profile.dev.package."*"]
 opt-level = 2
+
+[workspace.dependencies]
+thiserror = "1.0.37"