### 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)

case Variant::RECT2:
				return get_rect2(v);
			case Variant::RECT2I:
				return get_rect2i(v);
			case Variant::TRANSFORM3D:
				return get_transform(v);
			case Variant::PROJECTION:
				return get_projection(v);
			case Variant::TRANSFORM2D:
				return get_transform2d(v);
			case Variant::QUATERNION:
				return get_quaternion(v);
			case Variant::PLANE:
				return get_plane(v);
			case Variant::BASIS:
				return get_basis(v);
			case Variant::AABB:
				return get_aabb(v);
			case Variant::COLOR:
				return get_color(v);
			case Variant::STRING_NAME:
				return get_string_name(v);
			case Variant::NODE_PATH:
				return get_node_path(v);
			case Variant::RID:
				return get_rid(v);
			case Variant::CALLABLE:
				return get_callable(v);
			case Variant::SIGNAL:
				return get_signal(v);