feat: split packets definitions into separate assembly

Merge pull request #14 from Rutherther/packets-span

Rewrite packets string enumerator to use spans, add Injector for .NET 5+

feat: use ReadOnlySpan for deserialization instead of strings

refactor: split string converters

Merge pull request #12 from Rutherther/packets

Implement custom packet serializer

fix: correctly receive nullable type in serialize

fix: correctly return results from type converter repository

feat: add interfaces for serializers, converters