[jira] Detect when project has custom required fields and show error when creating Jira issue

We know that there's something about custom required fields which breaks our Jira integration's ability to create Jira issues from within sentry. It would be good if we could detect that someone is using custom required fields and show folks an error right away, rather than waiting for things to break.

Tasks:
- [ ] Figure out how to detect custom fields in the response data from jira
- [ ] Decide what we want to show on the FE when we detect this - should it just be a warning? Should we just refuse to let them create issues in that project? Are we even sure that it breaks in all scenarios?
- [ ] Add analytics to figure out how common this is