Write unit tests for existing Order MediatR methods

[iggy808]

• Create unit tests for CreateOrder_FromDto method
• Create unit tests for CreateOrderItems method
• Create unit tests for GetAllOrders_ToDto method

[iggy808]

Tests for CreateOrder_FromDto method potentially not blocked.

• If FindSync refactor is not a big issue, then progress may possibly proceed here

[iggy808]

Created unit test for CreateOrder_FromDto method

• Found out how to mock queries, refer to this test config to see how

[iggy808]

Done, closing