Survey the set of cases and edge cases we need to handle for locally scoped resource objects

[bogner]

There are various things that can be done with a resource variables - they can be passed to functions in parameters, defined in local arrays, assigned, etc.

RWBuffer<float> Buf;

[numthreads(1,1,1)]
void main() {
    RWBuffer<float> T = Buf;
    T[0] = 0;
}

We need to come up with a set of test cases and acceptance criteria to say we handle these correctly in clang so that we match what is possible in DXC, both in terms of accepted syntax and what generates valid DXIL.