Manually write binding for Surface.getCapabilities

[PyryM]

The C usage pattern for this function is idiosyncratic:
you're expected to create a WGPUSurfaceCapabilities, pass a pointer to it to wgpuSurfaceGetCapabilities(...),
which then sets internal pointers to arrays along with their element counts.

You do not own these arrays, instead when you're done you're expected to
free them with a separate function wgpuSurfaceCapabilitiesFreeMembers which takes the capabilities
struct by value and frees the internal pointers.

This is the only function in the API that works remotely like this so the binding has to be hand-written.