added a public setOrderOptedIn function

[creative-dev-lab]

Issue Report scenario is:

1. Customer buys a shirt and turns on AR. The OCP displays the AR widget, this is correct.
2. The next time they buy a notebook (the widget is still on for other eligible products eg shirts). The OCP displays the AR widget, which is not correct since it’s a notebook.

So my thought on this report is there isn't an actual issue in our SDK.
But The problem is that they decide to render the multi-opt-in widget after they got the eligibility result of the multi-opt-in widget by calling an exposed function named checkMultiOptInEligibility . and if it returns not-eligible, then they rather not render multi-opt-in widget on their end.
which means our SDK skips the operation of updating OrderOptedIn value.
So if OrderOptedIn was previously set as true , this value won't change in the above case, and on confirmation view, the widget will be automatically eligible.
This made the issue.

So I added another function called setOrderOptedIn to let them set the value manually on their end just for them.