Adding the total number of credible set for each study in the API

[prashantuniyal02]

The genetics team wants to view the total number of credible set for each study, as a column in the study table

Since, the study metadata does not contain that number. So we can do it as part of the API

Tasks

• [ ] Update it to include it in the GWAS Study table in the disease page
• [ ] Update it to include it in the Shared Trait Studies in the study page