SerializeCql is a confusing name for a macro

[Lorak-mmk]

As evidenced by #896 , SerializeCql is a confusing name for a macro that allows serializing UDT. It should be called SerializeUDT.

[piodul]

It is very common for derive macros to have exactly the same name as the trait they implement. To me at least, it's confusing when you write #[derive(SerializeUdt)] while there is no corresponding SerializeUdt trait.

Perhaps we could change both the trait and macro name to SerializeValue instead - that way it will be clear that it's about serializing values and not rows.

[wprzytula]

With @Lorak-mmk, we prefer the name change of both the trait and the derive macro to SerializeValue. We need to remember to rename the upcoming DeserializeCql to DeserializeValue as well.