popleft and popright should return value

[prshnt19]

Description of the problem

In liner_data_structures/linked_lists the pop_left and pop_right functions in return should also return value of the element to be popped.

Example of the problem

References/Other comments

[czgdp1807]

Queue has also a popleft method. Does that work correctly?

[prshnt19]

Currently, Queue is only implemented as ArrayQueue. It works correctly. Currently working on LinkedListQueue. I will use only the correct implementation.