Fix formatting of dlopen error message on Windows

[KamilBrzoskowski]

When developing GDExtension if there is a problem with dll loading you can get "not enough arguments for format string".
Reason for that is rather than using p_path as a parameter it is used to add to string, which causes vformat function to get one less parameter and sprintf to return error down the line.

[YuriSizov]

Good catch! Looks like a typo when someone converted the old string-concatenated message to vformat. Other platforms still use string concatenation, so it would be cool to change them to use vformat as well, and unify the message, since there are slight differences.

[akien-mga]

Other platforms still use string concatenation, so it would be cool to change them to use vformat as well, and unify the message, since there are slight differences.

I pushed an update to do that.

[akien-mga]

Thanks! And congrats for your first merged Godot contribution 🎉

[YuriSizov]

Cherry-picked for 4.1.1.