feature: event-driven updates

[sirugh]

Feature: Event Driven Updates instead of polling on interval

Today, the application is written to query for products and product changes on an interval. This can lead to excessive querying against the backend. Instead we should rewrite the application to use event-driven approach. This subscribes to events that are published from the commerce environment and then generates markup based on those change events.

[sirugh]

one consideration of event driven updates is back pressure due to incoming events being throttled by AEM limitations (600/minute on BYOM sources).

If the system receives 100,000 events, we still cannot process them all that quickly. Always, we are limited by EDS 600/minute.