Resolve notice.id / submission_id tensions for google

RE: redmine #7976

Includes:
* Copying a generated notice.id to submission_id when a notice has been
  submitted via a new-style web form or via the API.
* Increasing the start value of the notices_id_seq so legacy submission_ids
  don't clash with notice.id values generated in the new application

Todo:

- [ ] Confirm this will be adequate, given that there are non-google submissions in both the old and new chillingeffects sites