### Godot version

4.0.2.stable.official.7a0977ce2

### System information

Linux

### Issue description

The following code fails with godot-cpp
```c++
Variant variant_int = 1234;
double double_value = variant_int;
UtilityFunctions::print(double_value); // prints 0. it must be 1234

Variant double_variant = 6789.0;
int int_value = double_variant;
UtilityFunctions::print(int_value); // prints 0. it must be 1234

Variant variant_string = "12345";
StringName string_name = variant_string;
UtilityFunctions::print(string_name); // Segmentation Fault!
```

When godot-cpp converts a `Variant` to another type, it calls `type_from_variant_constructor` without checking its type. It only does  `reinterpret_cast` and does no type conversion.
I think this issue can be solved by implementing type conversion on the godot-cpp side or by making `type_from_variant_constructor` do the type conversion.

### Steps to reproduce

Unzip the minimal reproduction project and run `scons` to build the GDExtension.

### Minimal reproduction project

[variant-conversion-issue.zip](https://github.com/godotengine/godot/files/11171860/variant-conversion-issue.zip)

};
template <>
struct VariantZeroAssigner<Rect2> {
	static _FORCE_INLINE_ void zero(Variant *v) { *VariantInternal::get_rect2(v) = Rect2(); }
};
template <>
struct VariantZeroAssigner<Rect2i> {
	static _FORCE_INLINE_ void zero(Variant *v) { *VariantInternal::get_rect2i(v) = Rect2i(); }
};
template <>
struct VariantZeroAssigner<Vector3> {
	static _FORCE_INLINE_ void zero(Variant *v) { *VariantInternal::get_vector3(v) = Vector3(); }
};
template <>
struct VariantZeroAssigner<Vector3i> {
	static _FORCE_INLINE_ void zero(Variant *v) { *VariantInternal::get_vector3i(v) = Vector3i(); }
};
template <>
struct VariantZeroAssigner<Vector4> {
	static _FORCE_INLINE_ void zero(Variant *v) { *VariantInternal::get_vector4(v) = Vector4(); }
};
template <>
struct VariantZeroAssigner<Vector4i> {
	static _FORCE_INLINE_ void zero(Variant *v) { *VariantInternal::get_vector4i(v) = Vector4i(); }
};
template <>
struct VariantZeroAssigner<Transform2D> {
	static _FORCE_INLINE_ void zero(Variant *v) { *VariantInternal::get_transform2d(v) = Transform2D(); }