Better `set` for `abi.DynamicArray[abi.Byte]`

[barnjamin]

Problem

I'd like to put a byte string as the plain TealType.byte in a DynamicArray with set (or some other new method?)

Currently the easiest way I've found is either adding the length manually and calling decode or first creating an abi.String and calling set then byte_array.decode(s.encode())