Showed related topics under their groups #2862

- Issue Discreption:
Related_Topics in the topic class was split to multiple tags (Specialisation_of, Generalisation_of ...etc.) under the Related_Topics tag. 
It is required to show every topic group and the related topics listed under it in the "Related processes" field in the overview widget.  

-Issue Link on github: https://github.com/WormBase/website/issues/2862 .

-Test links : /resources/wbprocess/WBbiopr:00000040#0178b9--10 (Multiple related topics)
 /resources/wbprocess/WBbiopr:00000006?query=WBbiopr:00000006#0178b9--10 (single related topic)  

if you have an example of a Topic with multiple related topics under one group, please refer it to me. I couldn't find one.

-Questions:
In the related_process method in the API I created an Array of hashes(each one for a topics group), and every hash contains an array of the related topics.. array->hashes->array .. is it a good practice? Is it better to just return a hash of arrays?