Add type stubs for mido MIDI library

- Created type stubs for various modules in the mido library including messages, midifiles, parser, ports, sockets, syx, tokenizer, and version.
- Implemented type hints for functions and classes to improve type checking and code clarity.
- Added support for MIDI over TCP/IP in sockets module.
- Included methods for reading and writing SYX files in syx module.
- Enhanced the parser functionality with a dedicated Parser class for MIDI byte streams.
- Established a structure for MIDI file handling with MidiFile and MidiTrack classes.

typings/mido/frozen.pyi

@@ -0,0 +1,67 @@
+from typing import Never, TypeIs, overload, override
+
+from .messages import Message
+from .midifiles import MetaMessage, UnknownMetaMessage
+from .midifiles.meta import _MetaMessage  # pyright: ignore[reportPrivateUsage]
+
+class Frozen:
+    @override
+    def __setattr__(self, *_) -> Never: ...
+    @override
+    def __hash__(self) -> int: ...
+
+class FrozenMessage(Frozen, Message): ...
+class FrozenMetaMessage(Frozen, _MetaMessage): ...
+class FrozenUnknownMetaMessage(Frozen, UnknownMetaMessage): ...
+
+@overload
+def is_frozen(msg: UnknownMetaMessage) -> TypeIs[FrozenUnknownMetaMessage]: ...  # pyright: ignore[reportOverlappingOverload]
+@overload
+def is_frozen(msg: _MetaMessage) -> TypeIs[FrozenMetaMessage]: ...
+@overload
+def is_frozen(msg: Message) -> TypeIs[FrozenMessage]: ...
+@overload
+def is_frozen(msg: object) -> TypeIs[Frozen]:
+    """Return True if message is frozen, otherwise False."""
+
+@overload
+def freeze_message[T: Frozen](msg: T) -> T: ...
+@overload
+def freeze_message(msg: Message) -> FrozenMessage: ...
+@overload
+def freeze_message(msg: UnknownMetaMessage) -> FrozenUnknownMetaMessage: ...
+@overload
+def freeze_message(msg: MetaMessage) -> FrozenMetaMessage: ...
+@overload
+def freeze_message(msg: None) -> None: ...
+@overload
+def freeze_message[T: Frozen](
+    msg: T | Message | UnknownMetaMessage | MetaMessage | None,
+) -> T | FrozenMessage | FrozenUnknownMetaMessage | FrozenMetaMessage | None:
+    """Freeze message.
+
+    Returns a frozen version of the message. Frozen messages are
+    immutable, hashable and can be used as dictionary keys.
+
+    Will return None if called with None. This allows you to do things
+    like::
+
+        msg = freeze_message(port.poll())
+    """
+
+@overload
+def thaw_message(msg: FrozenUnknownMetaMessage) -> UnknownMetaMessage: ...
+@overload
+def thaw_message(msg: FrozenMetaMessage) -> MetaMessage: ...
+@overload
+def thaw_message(msg: FrozenMessage) -> Message: ...
+@overload
+def thaw_message(
+    msg: FrozenMessage | FrozenUnknownMetaMessage | FrozenMetaMessage,
+) -> Message | UnknownMetaMessage | MetaMessage:
+    """Thaw message.
+
+    Returns a mutable version of a frozen message.
+
+    Will return None if called with None.
+    """