feat(packets): pass nullable to packet serializers

feat(serializer): fix null representation as stated in #18

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 in inline deserializers

feat: use ReadOnlySpan for deserialization instead of strings

Merge pull request #16 from Rutherther/packets-list-inline-serializer

Add generation of packet list inline serializer

feat: accept types and variable names in inline converter generators instead of packet parameters

feat: use StringBuilder Append overloads

feat: split inline generated deserialization into different methods

Merge pull request #12 from Rutherther/packets

Implement custom packet serializer

chore: rename type generators to inline converter generators

feat: add inline packet converters generation support