WASM renderer isn't thread safe

[Elabajaba]

Bevy version

0.12 dev + wgpu 0.17

What went wrong

Wgpu types have been pretending to be Send + Sync on wasm despite being !Send + !Sync as it assumed wasm threading wasn't a thing, and it made using wpgu for native and wasm significantly easier.

Wasm threads are now starting to be used elsewhere, so wgpu has now changed it so that the types are still Send + Sync on native, but are now !Send + !Sync on wasm meaning that the renderer is now full of panics when targeting wasm because we're using #[derive(Resource)] on types that are !Send + !Sync

Additional information

See https://github.com/gfx-rs/wgpu/blob/trunk/CHANGELOG.md#wgpu-types-now-send-sync-on-wasm and gfx-rs/wgpu#3691