Local full-text search

Using the following components:

* [Elasticsearch](https://www.elastic.co/products/elasticsearch) the search database engine itself
* [fscrawler](https://github.com/dadoonet/fscrawler) the filesystem indexing tool

See https://wiki.samba.org/index.php/Spotlight_with_Elasticsearch_Backend for instructions. Also see https://wiki.freebsd.org/Elastic.

Then integrate it into the https://github.com/helloSystem/Menu.

`tracker` is not an option since it is Gnome, Xdg, D-Bus infested. Too many dependencies on [unwelcome technologies](https://github.com/helloSystem/hello/wiki/Welcome-and-unwelcome-technologies).