wrong Double to UInt256 conversion

Issue can be easily tested with this snippet:

double d = 1E+20d;
UInt256 u = (UInt256)d; 
Console.WriteLine(u);   // 0

The problem goes deeper to Lsh(in UInt256 x, int n, out UInt256 res) when in and out params are the same

        var u = new UInt256(1);
        UInt256.Lsh(in u, 1, out u);
        Console.WriteLine(u);   // 0

Resolved by https://github.com/NethermindEth/int256/pull/44 and https://github.com/NethermindEth/int256/pull/43 with full tests for all parameters