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/backends/backend.pyi

@@ -0,0 +1,119 @@
+from collections.abc import Callable
+from types import ModuleType
+
+from ..messages import BaseMessage
+from ..ports import BaseInput, BaseIOPort, BaseOutput, IOPort
+
+DEFAULT_BACKEND: str = "mido.backends.rtmidi"
+
+class Backend:
+    """
+    Wrapper for backend module.
+
+    A backend module implements classes for input and output ports for
+    a specific MIDI library. The Backend object wraps around the
+    object and provides convenient 'open_*()' and 'get_*_names()'
+    functions.
+    """
+
+    name: str
+    api: str | None
+    use_environ: bool
+    def __init__(
+        self, name: str | None = ..., api: str | None = ..., load: bool = False, use_environ: bool = True
+    ) -> None: ...
+    @property
+    def module(self) -> ModuleType:
+        """A reference module implementing the backend.
+
+        This will always be a valid reference to a module. Accessing
+        this property will load the module. Use .loaded to check if
+        the module is loaded.
+        """
+
+    @property
+    def loaded(self) -> bool:
+        """Return True if the module is loaded."""
+
+    def load(self) -> None:
+        """Load the module.
+
+        Does nothing if the module is already loaded.
+
+        This function will be called if you access the 'module'
+        property."""
+
+    def open_input(
+        self,
+        name: str | None = ...,
+        virtual: bool = False,
+        callback: Callable[[BaseMessage], object] | None = ...,
+        **kwargs: object,
+    ) -> BaseInput:
+        """Open an input port.
+
+        If the environment variable MIDO_DEFAULT_INPUT is set,
+        it will override the default port.
+
+        virtual=False
+          Passing True opens a new port that other applications can
+          connect to. Raises IOError if not supported by the backend.
+
+        callback=None
+          A callback function to be called when a new message arrives.
+          The function should take one argument (the message).
+          Raises IOError if not supported by the backend.
+        """
+
+    def open_output(
+        self, name: str | None = ..., virtual: bool = False, autoreset: bool = False, **kwargs: object
+    ) -> BaseOutput:
+        """Open an output port.
+
+        If the environment variable MIDO_DEFAULT_OUTPUT is set,
+        it will override the default port.
+
+        virtual=False
+          Passing True opens a new port that other applications can
+          connect to. Raises IOError if not supported by the backend.
+
+        autoreset=False
+          Automatically send all_notes_off and reset_all_controllers
+          on all channels. This is the same as calling `port.reset()`.
+        """
+
+    def open_ioport[TIn: BaseInput = BaseInput, TOut: BaseOutput = BaseOutput](
+        self,
+        name: str | None = ...,
+        virtual: bool = False,
+        callback: Callable[[BaseMessage], object] | None = ...,
+        autoreset: bool = False,
+        **kwargs: object,
+    ) -> BaseIOPort | IOPort[TIn, TOut]:
+        """Open a port for input and output.
+
+        If the environment variable MIDO_DEFAULT_IOPORT is set,
+        it will override the default port.
+
+        virtual=False
+          Passing True opens a new port that other applications can
+          connect to. Raises IOError if not supported by the backend.
+
+        callback=None
+          A callback function to be called when a new message arrives.
+          The function should take one argument (the message).
+          Raises IOError if not supported by the backend.
+
+        autoreset=False
+          Automatically send all_notes_off and reset_all_controllers
+          on all channels. This is the same as calling `port.reset()`.
+        """
+
+    def get_input_names(self, **kwargs: object) -> list[str]:
+        """Return a list of all input port names."""
+
+    def get_output_names(self, **kwargs: object) -> list[str]:
+        """Return a list of all output port names."""
+
+    def get_ioport_names(self, **kwargs: object) -> list[str]:
+        """Return a list of all I/O port names."""