Describe the pull request

Backports two recent fixes to version 0.4.2 for the Vulkan backend:

• An invalid image layout transition for present targets when using the Vulkan native swap chain while the D3D12 backend was also being enabled in the build.
• A static upper limit for unbounded descriptor arrays to (attempt to) prevent overflowing device limits when using multiple unbounded arrays. This can still occur, if too many of such descriptor arrays are bound at once, but the limit now gives more headroom. The actual upper bound can be granularly controlled in version 0.5.1 (see Add binding hints to shader reflection for unsupported scenarios. #167).

Related issues

Fixes were originally part of #165.