Adds request debounce option

[tjFogarty]

Thanks for a great package :)

This is in response to ticket #71 - it adds the option for requestDebounce which debounces the fetch method. By default it's not enabled.

It pulls in the debounce package, which has a minimal impact on bundle size: https://bundlephobia.com/[email protected]

Before:

After (300ms debounce set):