Support Algolia as drop-in search provider

[markdumay]

Is your feature request related to a problem? Please describe.
Hinode currently provides search functionality using FlexSearch, available in the module mod-flexsearch. It generates a search index that is exposed as a client-side script. Although this works for smaller sites, this creates significant overhead for larger sites.

Describe the solution you'd like
Algolia is popular hosted-search provider, used by gohugo.io, getbootstrap.com, and other sites. It provides several plans, including a free tier for open-source documentation sites. Ideally, the support for Algolia acts as a drop-in replacement for the existing mod-flexsearch, with minimal configuration.

Describe alternatives you've considered
FlexSearch is the currently supported alternative. Other search engines might be added in a later stadium.