* Progress towards deleting Sockets.Abstractions
- Moved our custom DefaultConnectionContext to Sockets.Http and renamed it to HttpConnectionContext.
- Renamed ConnectionManager to HttpConnectionManager
- Use DefaultConnection in tests and benchmarks
- Delete ConnectionMetadata
- React to rename of EndPoint to ConnectionHandler
- Rename UseSockets to UseConnections
- Rename MapEndPoint to MapConnectionHandler
- Rename HttpSocketOptions to HttpConnectionOptions