GO: Serialization
Following up #27 #1060 

documented in https://doc.kaitai.io/serialization.html

branches:

- https://github.com/kaitai-io/kaitai_struct_go_runtime/pull/28
- https://github.com/kaitai-io/kaitai_struct_compiler/pull/261
    -  base on https://github.com/kaitai-io/kaitai_struct_compiler/tree/serialization
- https://github.com/kaitai-io/kaitai_struct_tests/pull/101
    - base on https://github.com/kaitai-io/kaitai_struct_tests/tree/serialization



