[vk] Device creation refactor

[tangmi]

This PR is a refactor of the logical device creation code. The intention is to make it simpler and less error-prone to add feature/extension usage to the Vulkan backend by consolidating and re-using some of the logic.

• Moves PhysicalDevice into its own file
• Moves all the extension/feature related code into a new type, PhysicalDeviceFeatures
  • This type is reused both to query the device capabilities and as input to VkDeviceCreateInfo
  • Adds support for VkPhysicalDeviceVulkan12Features to test for and enable features in 1.2 when the extension may not be available.
  • Exclude extension-specific VkPhysicalDevice*Features structs if we're not requesting the corresponding extensions.
  • Request VK_KHR_sampler_mirror_clamp_to_edge when applicable. Closes #3651
• Pulls the VkPhysicalDeviceProperties and supported_extensions list into a new type, PhysicalDeviceInfo

PR checklist:

• [x] make succeeds (on *nix)
• [x] make reftests succeeds
• [x] tested examples with the following backends: bench, colour-uniform, compute, quad.
  • Also ran device initialization with VK_LAYER_LUNARG_device_simulation with a selection of device reports ranging across the different api versions.

[tangmi]

@kvark Apologies for the large PR! Since a lot of this PR is code moving around, I tried to move the move the files in separate commits as well as add comments in this PR to help point out where blocks within the file moved around. Hopefully this makes it easier to read--please let me know if there's anything else I can do to help legibility!

[kvark]

This makes sense! I noticed that the lib.rs had grown too big, and I'm happy to see all the physical device related stuff consolidated nicely now.

Reviewing this is hard, so there might be issues in there, which we discover later, but that's ok. bors r+

[bors[bot]]

Build succeeded:

• Android Stable
• Dependency Check
• iOS Stable
• MacOS Nightly
• MacOS Stable
• Ubuntu Nightly
• Ubuntu Stable
• Web Assembly
• Windows Nightly
• Windows Stable

[tangmi]

[...] there might be issues in there, which we discover later, but that's ok.

Don't hesitate to ping me on these issues--I'll try my best to support this code.