Allow Nodes, Resources, and TypedArrays to be exported

[chocola-mint]

This PR completes REG_PROPERTY's missing functionalities by allowing Nodes, Resources, and TypedArrays to be exported. #16 and #17 are addressed as well.

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To accomodate for REG_PROPERTY's new features, its meta properties have been refactored.

• REG_P_HintType and REG_P_HintString replace REG_P_Info, improving readability.
• REG_P_UsageFlags lets developers specify PropertyUsageFlags, a constexpr made up of bitflags OR'd together. This is passed into PropertyInfo verbatim.
• REG_P_ExportAsNode and REG_P_ExportAsResource tell RegAutomation to treat the property as a Node or a Resource type. It is theoretically possible to parse godot-cpp headers to figure out which types inherit from Node and which inherit from Resource, but this will lead to a huge amount of overhead and add a lot of code complexity, which is why this solution is picked.

A new class called PropertyBinder is extracted from Pattern_Property to handle binding logic. No tests are written for it yet, but example.h has been updated to feature demonstrations of the new features.

Test_PropertyParser on the other hand has been updated to make sure it can properly extract information from the REG_PROPERTY macro.

A notable difference between PropertyBinder and the previous Pattern_Property is that the mapping from C++ classes to Godot Variant enums is now a handwritten Dictionary. This is more maintainable than relying on naming patterns, and allows us to add in additional aliases as needed.

Lastly, the current implementation has just one limitation: It can't handle multidimensional arrays yet. The reasons are as follows:

• Multidimensional TypedArray<T> is just not supported by Godot at the moment. It won't compile.
• That leaves us with an Array on the C++ end, relying on PropertyHint and the right hint string to make the array appear as a typed multidimensional array to GDScript. However, the hint string in this situation would need to insert raw values of Variant enums, which is not possible with a mere C++ string literal.
  • Now obviously, having to lose type safety on the C++ end is enough reasons to discourage users from even trying this approach if it were hypothetically doable, nonetheless it's still a limitation.

The README has been updated with REG_PROPERTY's new features and the above limitation, along with a suggested workaround.