Promote guest users once they verify email (#1032)

Guest users who add an email address to their account and verify it get
promoted from "guest" user status to "regular" user status, so they can
now do things like becoming project managers, and so on.

backend/LexBoxApi/Controllers/LoginController.cs

@@ -161,6 +161,8 @@ public async Task<ActionResult<LexAuthUser>> VerifyEmail(
 
  user.Email = loggedInContext.User.Email;
  user.EmailVerified = true;
+ // Guest ussers are promoted to "regular" users once they verify an email address
+ user.CreatedById = null;
  user.UpdateUpdatedDate();
  await lexBoxDbContext.SaveChangesAsync();
  await RefreshJwt();