Consider templated add_malloc_device API

[EwanC]

We should consider whether we'd like a templated equivalent of our API for adding malloc nodes

node* add_malloc_device(void *&data, size_t numBytes, const std::vector<node>& dep = {});`

e.g

template <typename T>
node* add_malloc_device(void *&data, size_t count, const std::vector<node>& dep = {});

This is equivalent to template <typename T> T* sycl::malloc_device(count, ... and void* sycl::malloc_device(size_t numBytes,...

[EwanC]

Closing this as we now have a design for graph owner allocations in intel#18001