Support surface view formats without VK_KHR_swapchain_mutable_format

[beicause]

Connections
Fixes #10340

Description

Solution:

• Whether the swapchain images can carry view formats other than the surface format is now reported per surface by
  wgpu_hal::SurfaceCapabilities::native_view_formats.
• Vulkan reports false when VK_KHR_swapchain_mutable_format is unavailable, Metal and DX12 always report true, and GLES reports false. When the capability is missing, wgpu-core emulates the differing view formats by handing out an intermediate texture that is copied into the swapchain image when presenting. So vulkan now always supports SURFACE_VIEW_FORMATS.

Testing
examples/bug-repro/02_present_bugs can now exercise both the native and the emulated path with --emulate-view-formats, draw a clear pass into the sRGB view of the non-sRGB surface format with --draw-before-present, and keep presenting until the window is closed with --manual-close.
To manually test it:

cargo run -p wgpu-bug-repro-02-present-bugs -- --draw-before-present --manual-close --emulate-view-formats

Squash or Rebase?
Squash

Checklist

• I self-reviewed and fully understand this PR.
• CHANGELOG.md entries for the user-facing effects of this change are present.
• The PR is minimal, and doesn't make sense to land as multiple PRs.
• Commits are logically scoped and individually reviewable.
• The PR description has enough context to understand the motivation and solution implemented.
• (If applicable) WebGPU implementations built with wgpu may be affected behaviorally.
• (If applicable) Validation and feature gates are in place to confine behavioral changes.
• (If applicable) Tests demonstrate the validation and altered logic works.