wgpu template: wgpu 27.0.1 -> 29.0.1, winit FIXME

[goldnor]

This PR updates wgpu and completes the migration to winit 0.30.13, resolving existing FIXME comments and aligning the implementation with the latest upstream examples. The migration was primarily guided by the official wgpu example.

• winit migration: event loop is handled now by the implementation of the ApplicationHandler trait.
• wgpu major changes:
  • Surface::get_current_texture now returns CurrentSurfaceTexture enum, which simplifies the old MySwapchainManager::render method (now State::render)
  • InstanceDescriptor initialization APIs and display handle changes: Instance is now recreated on ApplicationHandler::resumed, as recommended for platforms with lifecycle management constraints (e.g. mobile; see ApplicationHandler::resumed)

[Firestar99]

The CI will fail, you have to run cargo xtask generate to update the generate directory. You can also add -x "cargo b" to build all of the variants generated or run whatever you want

[Firestar99]

Oh yea if you deleted a file, --clean or delete the entire generated directory. I like to keep it around to not delete the cargo lockfiles, which speeds up iteration with cargo xtask generate -x "cargo b" due to it not having to recompile from scratch every time.