Add Python code to spoof a `device_empty` function #56

[EmilyBourne]

Relevant Discussion

https://github.com/pyccel/pyccel-cuda/discussions/55 and discussion in the meeting on 13/6/2024

Describe the feature

I would like to be able to explicitly allocate memory on the CPU. In order to support this in pyccel-cuda we will create spoof functions which ensure that the code that the user writes runs correctly in Python

Test Code

Provide code which does not currently work but which should do when this issue is fixed:

import pyccel.cuda as cuda

if __name__ == '__main__':
     n = 100
     a = cuda.device_empty(n)

Proposed Solution

A function device_empty should be created in pyccel.cuda.array_allocation. It should be possible to import this function using the syntax import pyccel.cuda as cuda. The function should work like numpy.empty. For this issue it is not necessary for the translation to work