Rain Recurrence Time is a 'hidden' feature

Problem
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Rain recurrence time is an advanced feature with statistics not all of our users understand. Besides rain recurrence times become relevant for extreme rainfall events. Not all rainfall events.

Solution
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- [x] Hide rain recurrence card when not active
- [x] add a button of somesort to the rain/card or rain layer. whatevs
- [x] switch between get statistics or not. 
- [x] put data on the scope

TODO
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Rain recurrence time is a store and a type of store in the backend.. This is a hack.
To move forward:
- [x] Remove RRC aggregation type from nens/lizard-nxt --> https://github.com/nens/lizard-nxt/pull/560

:money_with_wings: