Persist issue form attributes on Issue Type change

This is a follow up from #331831 (closed)

Current Behavior

1. User clicks new issue
2. User enters title, description, assignees, milestone, labels, due date etc.
3. User changes type to incident
4. Only the title and description fields are recovered. Other fields the user entered when they created the issue disappear until changing back to type: issue

Proposal

Persist all fields on the new issue form when the issue type changes from issue -> incident, including title, description, assignees, milestone, labels, due date. Essentially, when the issue type is changed, everything else in the form should stay the same, only the issue type should change.