Fix some wgpu/egui-winit errors and warnings

[hannobraun]

wgpu and egui-winit emits quite a few warnings! Here's what I'm seeing as of before this pull request:

  2022-10-13T11:10:11.381181Z ERROR wgpu_hal::vulkan::instance: VALIDATION [UNASSIGNED-CoreValidation-Shader-InconsistentSpirv (0x6bbb14)]
        Validation Error: [ UNASSIGNED-CoreValidation-Shader-InconsistentSpirv ] Object 0: handle = 0x55e13b1add70, type = VK_OBJECT_TYPE_DEVICE; | MessageID = 0x6bbb14 | SPIR-V module not valid: [VUID-StandaloneSpirv-Flat-06202] OpEntryPoint interfaces variable must not be vertex execution model with an input storage class for Entry Point id 107.
  %a_color = OpVariable %_ptr_Input_uint Input

    at /home/hanno/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/wgpu-hal-0.13.2/src/vulkan/instance.rs:48

  2022-10-13T11:10:11.381248Z ERROR wgpu_hal::vulkan::instance:         objects: (type: DEVICE, hndl: 0x55e13b1add70, name: ?)
    at /home/hanno/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/wgpu-hal-0.13.2/src/vulkan/instance.rs:111

  2022-10-13T11:10:11.382990Z ERROR egui_winit::clipboard: Cannot initialize smithay clipboard without a display handle!
    at /home/hanno/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/egui-winit-0.19.0/src/clipboard.rs:139

  2022-10-13T11:10:12.303601Z  WARN wgpu_core::device: Requested size 800x600 is outside of the supported range: Extent3d { width: 3840, height: 2022, depth_or_array_layers: 1 }..=Extent3d { width: 3840, height: 2022, depth_or_array_layers: 1 }
    at /home/hanno/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/wgpu-core-0.13.2/src/device/mod.rs:4974

  2022-10-13T11:10:12.303839Z ERROR wgpu_hal::vulkan::instance: VALIDATION [VUID-VkSwapchainCreateInfoKHR-imageExtent-01274 (0x7cd0911d)]
        Validation Error: [ VUID-VkSwapchainCreateInfoKHR-imageExtent-01274 ] Object 0: handle = 0x55e13b1add70, type = VK_OBJECT_TYPE_DEVICE; | MessageID = 0x7cd0911d | vkCreateSwapchainKHR() called with imageExtent = (800,600), which is outside the bounds returned by vkGetPhysicalDeviceSurfaceCapabilitiesKHR(): currentExtent = (3840,2022), minImageExtent = (3840,2022), maxImageExtent = (3840,2022). The Vulkan spec states: imageExtent must be between minImageExtent and maxImageExtent, inclusive, where minImageExtent and maxImageExtent are members of the VkSurfaceCapabilitiesKHR structure returned by vkGetPhysicalDeviceSurfaceCapabilitiesKHR for the surface (https://www.khronos.org/registry/vulkan/specs/1.3-extensions/html/vkspec.html#VUID-VkSwapchainCreateInfoKHR-imageExtent-01274)
    at /home/hanno/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/wgpu-hal-0.13.2/src/vulkan/instance.rs:48

  2022-10-13T11:10:12.303880Z ERROR wgpu_hal::vulkan::instance:         objects: (type: DEVICE, hndl: 0x55e13b1add70, name: ?)
    at /home/hanno/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/wgpu-hal-0.13.2/src/vulkan/instance.rs:111

With the fixes from this pull request, I'm down to this:

  2022-10-13T11:11:39.523521Z ERROR wgpu_hal::vulkan::instance: VALIDATION [UNASSIGNED-CoreValidation-Shader-InconsistentSpirv (0x6bbb14)]
        Validation Error: [ UNASSIGNED-CoreValidation-Shader-InconsistentSpirv ] Object 0: handle = 0x55cbf113afb0, type = VK_OBJECT_TYPE_DEVICE; | MessageID = 0x6bbb14 | SPIR-V module not valid: [VUID-StandaloneSpirv-Flat-06202] OpEntryPoint interfaces variable must not be vertex execution model with an input storage class for Entry Point id 107.
  %a_color = OpVariable %_ptr_Input_uint Input

    at /home/hanno/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/wgpu-hal-0.13.2/src/vulkan/instance.rs:48

  2022-10-13T11:11:39.523642Z ERROR wgpu_hal::vulkan::instance:         objects: (type: DEVICE, hndl: 0x55cbf113afb0, name: ?)
    at /home/hanno/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/wgpu-hal-0.13.2/src/vulkan/instance.rs:111

Both of those remaining errors seem to be caused by gfx-rs/naga#2036. This is already fixed, so they should disappear too, once we upgrade to the latest wgpu (#976).