try_from_variant does not handle errors

[ttencate]

Despite returning Result, this can never return Err:

https://github.com/godot-rust/gdextension/blob/154b87f3340080d9c19d0e84d5e8e9859ef25ff5/godot-core/src/builtin/variant/impls.rs#L45-L60

The comment is stale as well, because from_sys_init now initializes with Default for types that need it (e.g. Array, GodotString).