feat(python): add full type annotations support with default enabled

[mblsha]

This commit implements comprehensive Python type annotation support for the Kaitai Struct compiler, making it the default behavior for modern Python development while maintaining backward compatibility.

• Type Annotations by Default: Python code now generates with full type annotations enabled by default

• Comprehensive Coverage: Type annotations for constructors, methods, properties, and all data types

• Modern Python Support: Imports typing module and uses modern annotation syntax

• Backward Compatibility: New --no-python-type-annotations flag to disable when needed

• Added pythonTypeAnnotations: Boolean = true to RuntimeConfig (default: true)

• Created comprehensive kaitaiTypeToPythonType() mapping function

• Enhanced constructor with full parameter and instance variable annotations

• Added return type annotations for all methods (_read, properties, repr)

• Conditional typing imports only when annotations enabled

• Removed "# type: ignore" comment when annotations are present

With type annotations (default):

from typing import Any, List, Optional, Union

def __init__(self, _io: 'KaitaiStream', _parent: 'KaitaiStruct' = None,
             _root: Optional['KaitaiStruct'] = None) -> None:
    self._io: 'KaitaiStream' = _io
    self._parent: 'KaitaiStruct' = _parent

@property
def calculated_value(self) -> int:
    return self.magic * 2

Without annotations (--no-python-type-annotations):

def __init__(self, _io, _parent=None, _root=None):
    self._io = _io
    self._parent = _parent

• --python-type-annotations: Explicitly enable (now redundant but supported)
• --no-python-type-annotations: Disable type annotations
• Default behavior: Type annotations enabled