feat: improved handling of shapes

[mrava87]

This PR improves the handling of global_shape and local_shapes in DistributedArray, allowing one to pass integers instead of tuples for 1D array:

• For global_shape this was already allowed, but a bug has been identified when local_shapes!=None since in _check_local_shapes this is indexed - see

  pylops-mpi/pylops_mpi/DistributedArray.py

  Line 325 in 6d3b1e8

  if self._allreduce(local_shape[self.axis]) != self.global_shape[self.axis] or \

• For local_shapes, this is a new feature

[mrava87]

@rohanbabbar04 just checking you saw this :)

[rohanbabbar04]

@rohanbabbar04 just checking you saw this :)

Let me test this, I will get back on this tomorrow :)

[rohanbabbar04]

@mrava87,
It looks good to merge