Migrate to using `button` elements instead of `a` elements with button styling

[di]

          > Seems like maybe we should be using `button` elements everywhere instead of `a` elements?

Yes, we likely should be using button since then we can take advantage of that, as well as any semantic HTML/screen readers

That's a larger change - and would need changes in blocks/_buttons.scss as well as the macro confirm_button/confirm_password_button generators in manage_base.html

Originally posted by @miketheman in #14244 (comment)