refactor: create the types subpackage, and the jsonrpc module (#1918)

Author: Kludex

src/mcp/server/session.py

@@ -42,7 +42,7 @@ async def handle_list_prompts(ctx: RequestContext) -> list[types.Prompt]:
 import anyio
 import anyio.lowlevel
 from anyio.streams.memory import MemoryObjectReceiveStream, MemoryObjectSendStream
-from pydantic import AnyUrl
+from pydantic import AnyUrl, TypeAdapter
 
 import mcp.types as types
 from mcp.server.experimental.session_features import ExperimentalServerSessionFeatures
@@ -105,11 +105,11 @@ def __init__(
         self._exit_stack.push_async_callback(lambda: self._incoming_message_stream_reader.aclose())
 
     @property
-    def _receive_request_adapter(self) -> types.TypeAdapter[types.ClientRequest]:
+    def _receive_request_adapter(self) -> TypeAdapter[types.ClientRequest]:
         return types.client_request_adapter
 
     @property
-    def _receive_notification_adapter(self) -> types.TypeAdapter[types.ClientNotification]:
+    def _receive_notification_adapter(self) -> TypeAdapter[types.ClientNotification]:
         return types.client_notification_adapter
 
     @property