Implement streaming to load catalogue queries

[xamcost]

Hi there! Since #37 we have a running catalogue, however, each catalogue query makes three requests to fetch offerings, their providers and corresponding keywords. The goal of this issue is to improve the user experience when a query is done, by leveraging Nextjs streaming. That way, we can use Suspense components to first load the offerings, and then the providers and keywords.

This issue shouldn't be prioritized for now, unless requested by partners/test users.