Base OScriptNodePin on PropertyInfo

[Naros]

Description

Godot encodes quite a bit of information in its ProperyInfo struct, which describes a property on a class or a method argument or return value. If we transition OScriptNodePin to be based on this structure, this has a number of benefits such as making the integration of function calls much more seamless.

Implementation ideas

Change OScriptNodePin class members to look something like this:

PropertyInfo _property;
EPinType _pin_type;
EPinDirection _direction;
Variant _default_value;
Variant _generated_default_value;
BitField<Flags> _flags;
String _user_friendly_name;
String _member_parent_class; 

Many properties like _pin_name, _type, _target_class, as well as some of the flag bits would get encoded into the new PropertyInfo member named _property. Additionally, this would begin to serialize hint and usage flags along with the hint string, which allows the _file_types variable to become persistent.

In some instances, it may be useful for a pin to reference to a member in a specific target class. I'd prefer we consider folding part of the intent of _target_class into the PropertyInfo's class_name attribute; which keeping the other potential intent to describe the class that owns the property to be enabled into the new attribute called _member_parent_class or perhaps _owner_class or something similar.

In addition, all create_pin functions should be changed in OScriptNode. They should prefer to encapsulate as much behavior as possible, ideally having the node define whether the pin is (a) execution/data and (b) the property info associated with the pin; with an optional default value.