feat(c_sharp) add @assignment support for all possible assignable statements

[prashanthsp6498]

Supports for all assignment statements.

Lambda Method

    public static string Method() => $"return result";

class/struct/record fields

    const int CONST_FIELD = 10;
    public static Node head;
    public static Node tempHead = new Node();

local variables declarations

    int count = 10;
    int[] arr = new int[] {1, 2, 3, 4, 5, 6};
    head = new Node{data = arr[0]};
    count = 100;

Above local fields also support in field scope