### 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)

static const Vector4i *get_ptr(const Variant *v) { return VariantInternal::get_vector4i(v); }
};
template <>
struct VariantGetInternalPtr<Transform2D> {
	static Transform2D *get_ptr(Variant *v) { return VariantInternal::get_transform2d(v); }
	static const Transform2D *get_ptr(const Variant *v) { return VariantInternal::get_transform2d(v); }
};
template <>
struct VariantGetInternalPtr<Transform3D> {
	static Transform3D *get_ptr(Variant *v) { return VariantInternal::get_transform(v); }
	static const Transform3D *get_ptr(const Variant *v) { return VariantInternal::get_transform(v); }
};
template <>
struct VariantGetInternalPtr<Projection> {
	static Projection *get_ptr(Variant *v) { return VariantInternal::get_projection(v); }
	static const Projection *get_ptr(const Variant *v) { return VariantInternal::get_projection(v); }
};
template <>
struct VariantGetInternalPtr<Plane> {
	static Plane *get_ptr(Variant *v) { return VariantInternal::get_plane(v); }
	static const Plane *get_ptr(const Variant *v) { return VariantInternal::get_plane(v); }
};
template <>
struct VariantGetInternalPtr<Quaternion> {
	static Quaternion *get_ptr(Variant *v) { return VariantInternal::get_quaternion(v); }
	static const Quaternion *get_ptr(const Variant *v) { return VariantInternal::get_quaternion(v); }
};
template <>
struct VariantGetInternalPtr<::AABB> {
	static ::AABB *get_ptr(Variant *v) { return VariantInternal::get_aabb(v); }