feat(packets): accept ReadOnlySpan instead of string in serializer

Merge pull request #47 from Rutherther/feat/pass-nullable

Pass CanBeNull to string serializer and converter

feat(packets): pass nullable to packet serializers

chore: move PacketSerializer types to correct namespace

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

Merge pull request #12 from Rutherther/packets

Implement custom packet serializer

fix: accept interface types repositories

feat: implement packet serializer

feat: add interfaces for serializers, converters

feat: add base packet types converting