Creates a new Bytes from data.
After this call, data belongs to the bytes and may no longer be modified by the caller. 
            g_free will be called on data when the bytes is no longer in use. Because of 
            this data must have been created by a call to malloc, 
            malloc0 or realloc or by one of the many 
            functions that wrap these calls (such as g_new, BusName, etc)
            .
For creating Bytes with memory from other allocators, see new_with_owner.
data may be null if data.length is 0.
| data | the data to be used for the bytes | 
| size | the size of  | 
| a new Bytes |