Port Endlagersuche Infoplattform to Rust

This is currently our smallest Python harvester and hence easily ported. In addition, it is in dire need of extracting text from PDF which we will most likely implement only in Rust. It is therefore a prerequisite to port the harvester as well.

In addition, the code is restructured to take the usual form we use for pagination and the extraction of titles and time ranges is improved slightly.