Page Impression Instance Amendments

With a review of the data we have consumed, the following amendments have been implemented to increase the relevancy of the data:

- [ ] Implement a `page impression id` attribute, to clearly distinguish a single page impression from another
- [ ] Rename Flamsteed page impression options to clearly denote the `session id` from the `page impression id`
- [ ] Enable `schema` on the Flamsteed page impression instance
- [ ] Remove `RUM` calculations on client and send through only raw values
- [ ] Ensure `key=value` pairs are correctly populated and sanitized
Good spot.