by 凤之兮原 @kongmingLatern
Get the middle element of the array by implementing a GetMiddleElement method, represented by an array
If the length of the array is odd, return the middle element If the length of the array is even, return the middle two elements
For example
type simple1 = GetMiddleElement<[1, 2, 3, 4, 5]>, // expected to be [3]
type simple2 = GetMiddleElement<[1, 2, 3, 4, 5, 6]> // expected to be [3, 4]
