Fixes to get shader-object example working on CUDA (#1708)

The purpose of these changes is to make the `shader-object` example work correctly on CUDA.

Originally I had tried to add changes to the "flat" reflection information so that it introduced descriptor ranges to match the binding ranges it added for interface/existential-type fields. This approach helped the CUDA code that was using that information to try and compute uniform offsets for those fields, but it broke most of the other renderer back-ends. Instead, I removed the relevant asserts from `CUDAShaderObject::setObject()`.

Note taht there are leftover changes from my edits to the flat reflection information, around how it handles "leaf" fields that consume multiple resource kinds. I believe that those changes are, on balance, "more correct" now than they were before, so I decided to leave them in.

The other major fix here is to specialize the `CUDAShaderObject::setObject()` logic to handle the case of setting a shader object for a parameter that has interface type instead of a constant-buffer or parameter block. Mostly I just copy bytes from the child object into the parent object. There are a few caveats, though:

* I am not writing the RTTI or witness-table information, so dynamic dispatch won't work.

* I am assuming a hard-coded offset of 16 bytes for the any-value, which will work for now but is a bit too "magical" and might also break once we support conjunctions of interfaces with dynamic dispatch

* I am assuming that the child value to be writen into the field will "fit" into the any-value area. We need some way to determine whether or not things fit dynamically (ideally using the reflection data), and adapt accordingly.

* I had to add another method on the base CUDA shader object type to handle setting data using a device-memory pointr instead of a host-memory pointer

* There's not a lot we can do about it, but in the case of assigning an ordinary `CUDAShaderObject` into an interface-type field of a `CUDAEntryPointShaderObject` we end up needing to perform a device->host memory copy, because the bytes of the value will have already been written to GPU memory, but need to be in GPU memory for the dispatch call.

* The implementation I'm using here basically assumes that the child shader object must have been finalized before it gets plugged into the parent shader object. We haven't yet made a policy decision about that bit.

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