Add script to generate a raw cgo-level interface for go-nvml

This interface can be used in conjunction with the standard "wrapper"
interface, including the use its interface abstractions like Devices,
GPUInstances, ComputeInstances, etc.

It is invoked as nvml.CgoAPI.<api-call>, following the original function
signatures of the C-API, where there is only a single return value and
additional return values are passed as arguments.

An example usage is:
```
	// Start with using the CgoAPI
	ret := nvml.CgoAPI.Init()
	defer nvml.Shutdown()
	require.Equal(t, SUCCESS, ret, "Init should succeed")

	var count uint32
	ret = nvml.CgoAPI.DeviceGetCount(&count)
	require.Equal(t, SUCCESS, ret, "DeviceGetCount should succeed")

	var device Device
	ret = nvml.CgoAPI.DeviceGetHandleByIndex(0, &device)
	require.Equal(t, SUCCESS, ret, "DeviceGetHandleByIndex should succeed")

	// Now call Device interface methods directly
	name, ret := device.GetName()
	require.Equal(t, SUCCESS, ret, "Device.GetName should succeed")
	t.Logf("Device.GetName: %s", name)

	uuid, ret := device.GetUUID()
	require.Equal(t, SUCCESS, ret, "Device.GetUUID should succeed")
	t.Logf("Device.GetUUID: %s", uuid)

	brand, ret := device.GetBrand()
	require.Equal(t, SUCCESS, ret, "Device.GetBrand should succeed")
	t.Logf("Device.GetBrand: %v", brand)

	busType, ret := device.GetBusType()
	require.Equal(t, SUCCESS, ret, "Device.GetBusType should succeed")
	t.Logf("Device.GetBusType: %v", busType)
```

Signed-off-by: Kevin Klues <[email protected]>

Author: klueska