feat(insights): expose internal client through eventTracker

[dhayab]

Q	A
Bug fix?	no
New feature?	yes
BC breaks?	no
Related Issue	Slack
Need Doc update	yes

Describe your change

This exposes the Insights client created within the algolia_insights helper so it can be used to push events that are unsupported by the helper at this time.

Example usage

searcher.eventTracker?.client.pushEvents(
  insightsEvents: InsightsEvents(events: [
    AddedToCartObjectIDs(
      eventName: 'eventName',
      eventType: ConversionEvent.conversion,
      eventSubtype: AddToCartEvent.addToCart,
      index: 'instant_search',
      objectIDs: ['objectID1', 'objectID2'],
      userToken: 'userToken')
]));

[aallam]

The issue with exposing (and using) the client directly is that it doesn't handle the offline case. That's why the insights flutter package exists.

[dhayab]

Thanks @aallam for the feedback!

From what I understand, the better way to handle the gap we're facing it to update all of the insights helper types and methods to handle the missing event types and subtypes.

Until we have the resources to comprehensively address it, do you think this PR work as a stop-gap measure if we ensure users understand that by directly accessing the insights client they don't benefit from the offline capability?

[aallam]

Until we have the resources to comprehensively address it, do you think this PR work as a stop-gap measure if we ensure users understand that by directly accessing the insights client they don't benefit from the offline capability?

Yeah, sure it could be. It is also possible for users to instantiate their own instance of the client if they wish.
In all cases, it must be clear that events sent directly through the client are executed immediately. If a call fails, there will be no further retries. That's the main reason for using the helper.