API endpoint limitation

The present implementation is limited to the /categ and /event endpoint while generally, search are conducted across the whole indico.

In details

• search_events presently uses the /categ endpoint and launches a request only using the categoryID, then filters through the results
• search_events_by_term does the same, and again filters through any number of event it is getting This makes the search non-functional unless we provide the right category and get all the events in the response

I propose to rework the tools for

• search_events_by_term
  • uses the endpont event/search
• search_events_in_category
  • use the present implementation of search_events_by_term

Also, I wonder if the search_categories is functional because the api just takes an ID and again it is the code that is supposed to filter through it all.