Bug fix multiple runtimes

[nsmithtt]

• For some reason the cmake variables for toggling different runtimes were not working for me. Only the TTNN runtime was able to be enabled.
• We also need to set the runtime before we open the device, otherwise the device and the rest of the runtime will mismatch.
• For now we also just hardcode ttrt to be single device

[nsmithtt]

@jnie-TT, I'm actually glad we got bit by this right away! What happened was that we called open_device above which opens a ttnn device, then we ttrt.runtime.set_compatible_runtime(fbb) to ttmetal runtime and boom!

Can you file an issue to track this? We could do something like:

enum class DeviceRuntime {    
  Disabled,    
  TTNN,    
  TTMetal,    
}; 

struct ObjectImpl {             
  DeviceRuntime runtime;                                                                                                                                                               
  std::shared_ptr<void> handle;                                                                                                                                                      
                                                                                                                                                                                    
  ObjectImpl(std::shared_ptr<void> handle) : handle(handle) {}                                                                                                                                           
  template <DeviceRuntime R, typename T> T &as() { assert(associatedRuntime == R); return *static_cast<T *>(handle.get()); }                                                                                                                     
  template <DeviceRuntime R, typename T> T const &as() const {                  
    assert(associatedRuntime == R);                                                                                                                      
    return *static_cast<T const *>(handle.get());                                                                                                                                    
  }                                                                                                                                                                             
};

Let's just make it impossible to mix types between the two runtime worlds.

[jnie-TT]

@nsmithtt great catch! I filed an issue #331