Library iris.prelude.options

Coq configuration for Iris (not meant to leak to clients). If you are a user of Iris, note that importing this file means you are implicitly opting-in to every new option we will add here in the future. We are *not* guaranteeing any kind of stability here. Instead our advice is for you to have your own options file; then you can re-export the Iris file there but if we ever add an option you disagree with you can easily overwrite it in one central location.