Implement TryConvertFrom<Iterator<Item=f64>> for Matrix

[Janmajayamall]

1. I wanted to implement try_convert_from from Iterator<Item=f64> to Matrix. Couldn't figure out the right way to do so. After implementing this we can removeCastToZp<Uint> for F trait bound (& CastToZp trait itself) in simd_encode (inside ckks/ops.rs) and instead use TryConvertFrom<Iterator<Item=f64>> for Matrix
2. No [f64] instead will not work. This is because f64 values are not stored as a slice and can only be converted to a Iterator