Replacing ModelMapper with MapStruct

- Removed Model Mapper from pom files
- Replaced ModelMapper with MapStruct
- Added Tests for MapStruct
- Changed mapstruct annotations for individual variables to be null safe rather than all variables
- Excluded generated code from code coverage
- Set ModuleReferences input to required for SchemaSet so that ModuleReferences list set to empty list rather than null

Issue-ID: CPS-127
Signed-off-by: lukegleeson <luke.gleeson@est.tech>
Change-Id: I43f874aea79f58dda5526c6fdead27d8474d90af