refs TryGhost/Team#1907
- calculates final attribution source and medium using captured referrer information in history
- adds new referrer-translator that goes through available history and based to determine most valid referrer info
- includes referrer url, source and medium in the attribution data for storage
refs https://github.com/TryGhost/Team/issues/1899
- Added `addEmailAttributionToUrl` method to MemberAttributionService. This adds both the source attribution (`rel=newsletter`) and member attribution (`?attribution_id=123&attribution_type=post`) to a URL.
- The URLHistory can now contain a new sort of items: `{type: 'post', id: 'post-id', time: 123}`.
- Updated frontend script to read `?attribution_id=123&attribution_type=post` from the URL and add it to the URLHistory + clear it from the URL.
- Wired up some external dependencies to LinkReplacementService and added some dummy code.
- Increased test coverage of attribution service
- Moved all logic that removes the subdirectory from a URL to the UrlTranslator instead of the AttributionBuilder
- The UrlTranslator now parses a URLHistoryItem to an object that can be used to build an Attribution instance
- Excluded sites with different domain from member id and attribution tracking
In case there is an issue with the filtering of items in our client
side attribution script, we also check for and remove out of date
items here. This ensures that we do not erroneously attribute signups
or conversions to webpages from more than 24h ago.
This keeps the constructor clean, relying on types for validation,
whilst preserving the validation when creating the instance. The
constructor is now private so that the factory which handles
validation is always used.
The tests have also been updated to test the public factory interface
rather than the internal validation methods. Validation has been
rolled into a single method and slightly improved in the way of
readability.
refs https://github.com/TryGhost/Team/issues/1808
refs https://github.com/TryGhost/Team/issues/1809
refs https://github.com/TryGhost/Team/issues/1820
refs https://github.com/TryGhost/Team/issues/1814
### Changes in `member-events` package
- Added MemberCreatedEvent (event, not model)
- Added SubscriptionCreatedEvent (event, not model)
### Added `member-attribution` package (new)
- Added the AttributionBuilder class which is able to convert a url history to an attribution object (exposed as getAttribution on the service itself, which handles the dependencies)
```
[{
"path": "/",
"time": 123
}]
```
to
```
{
"url": "/",
"id": null,
"type": "url"
}
```
- event handler listens for MemberCreatedEvent and SubscriptionCreatedEvent and creates the corresponding models in the database.
### Changes in `members-api` package
- Added urlHistory to `sendMagicLink` endpoint body + convert the urlHistory to an attribution object that is stored in the tokenData of the magic link (sent by Portal in this PR: https://github.com/TryGhost/Portal/pull/256).
- Added urlHistory to `createCheckoutSession` endpoint + convert the urlHistory to attribution keys that are saved in the Stripe Session metadata (sent by Portal in this PR: https://github.com/TryGhost/Portal/pull/256).
- Added attribution data property to member repository's create method (when a member is created)
- Dispatch MemberCreatedEvent with attribution
### Changes in `members-stripe-service` package (`ghost/stripe`)
- Dispatch SubscriptionCreatedEvent in WebhookController on subscription checkout (with attribution from session metadata)
