search analytics framework

[maxim-uvarov]

For fine tuning we need to gather usage date of the search.
The major goal is to provide data for monitoring of:

• coverage (queries vs results)
• quality (queries vs results)
• user retention

So we need to find the orthodox way of collecting such data that would not contradict our privacy focused principles.

A simple decision would be to use self hosted analytics like piwik. But as for now @mastercyb and @litvintech reject this option.

[mastercyb]

implemented https://metrics.cyb.ai/cyb.ai but its not the solution for analytics