feat: Add incremental delivery support for @defer and @stream directives

[jwaldrip]

Summary

This PR adds incremental delivery support to absinthe_graphql_ws for @defer and @stream directives.

⚠️ DEPENDENCY NOTICE

This PR depends on gigsmart/absinthe#gigmart/defer-stream-incremental
The main absinthe package must be merged first before this PR can be merged.

Features

• GraphQL-WS protocol transport for incremental delivery
• Uses Next/Complete messages for proper protocol compliance
• Transport extensions for handling streaming responses
• Maintains WebSocket connection efficiency during streaming

Implementation

• Absinthe.GraphQL.WS.Incremental.Transport - Main transport adapter
• Absinthe.GraphQL.WS.TransportExtensions - Protocol extensions

Testing

• Protocol compliance tests
• Message sequencing validation
• Error handling scenarios

Breaking Changes

None - incremental delivery is opt-in and backward compatible.