[FEATURE] Update From trait implementation for the RawNtpPacket

[vpetrigo]

Is your feature request related to a problem? Please describe.
Currently there are two lambdas that converts u32 and u64 into an array:

    fn from(val: RawNtpPacket) -> Self {
        // left it here for a while, maybe in future Rust releases there
        // will be a way to use such a generic function with compile-time
        // size determination
        // const fn to_array<T: Sized>(x: &[u8]) -> [u8; mem::size_of::<T>()] {
        //     let mut temp_buf = [0u8; mem::size_of::<T>()];
        //
        //     temp_buf.copy_from_slice(x);
        //     temp_buf
        // }
        let to_array_u32 = |x: &[u8]| {
            let mut temp_buf = [0u8; mem::size_of::<u32>()];
            temp_buf.copy_from_slice(x);
            temp_buf
        };
        let to_array_u64 = |x: &[u8]| {
            let mut temp_buf = [0u8; mem::size_of::<u64>()];
            temp_buf.copy_from_slice(x);
            temp_buf
        };

Describe the solution you'd like
When this rust-lang/rust#43408 would be resolved let's update the implementation with generic size_of::<T>() usage.

Describe alternatives you've considered
N/A

Additional context
N/A