None of the above options. To me, all the proposed spinner locations feel like the wrong context, I have a solution that works for RTL users as well as everybody else!
When you add the spinner to a button, in place of text, or inside page content like this you arent necessarily telling your user that they must wait, you are adding a spinning image as content, and they have to guess what it means.
Instead of adding the spinner as page content, what if you disabled the button, and displayed the spinner (just for a moment) over the middle of the page, on top of an overlay. This keeps the spinner outside of the site content, and indicates to the user that this layout is in a different state: loading.
A centred, overlaid spinner also gets around your LTR and RTL issues as both users see a centred item the same way ☺️