Implement server-side search demo

[mrtag23]

Implemented in https://github.com/ffw-us/next-contentful-starterkit/pull/24

[asgorobets]

Another interesting future consideration, Typesense claims to be Open Sourcr alternative to algolia and comes with adapters to use Instasearch as well: https://typesense.org/docs/guide/search-ui-components.html#using-instantsearch-js