Feat: EXP-4851 - Add optimizely attribute fetch function

[patrick-wu]

Summary

Adding the following to the Rokt kit:

• ingesting new settings field that indicates whether there's a onboardingExpProvider
• new function for fetching optimizely experiments and transforming them to select-placement attributes
• before selectPlacement(), executes the Optimizely attribute fetch function and attach Optimizely attributes to the SP call

Testing Plan

tested locally