Is your feature request related to a problem? Please describe.
A number of advanced use cases want to use wgpu as an API for rendering, but with advanced features which shouldn't need an API in wgpu. For example, #7317, #6149, VK_ANDROID_external_memory_android_hardware_buffer. However, currently this involves adding things into wgpu's Vulkan device creation (as a PR to this repo). This is... awkward.

Describe the solution you'd like
Research into how to make this work. @cwfitzgerald mentions that this also involves enabling "features" in the extensions, which makes this messy?

Describe alternatives you've considered

• Use raw Vulkan. No thank you
• Make it possible to construct a wgpu Device from a user-provided Vulkan Device (maybe?). This seems very complicated. Heavily related to Proposal for Underlying Api Interoperability #4067, but smaller scoped