HPPC-8551 Start refactoring the serialization functions

- Introduce two serialization functions in the IOutputMetaData
- Rename and rationalise some of the existing functions
- Start work on dictionary serialization functions

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
checkpoint1 - compiling

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>