KISS the serratus API

[almosnow]

As the serratus API was developed, many features were added for which API routes (and backed methods) exist, some of these overlap or are relatively complex to grasp. As an example, the frontend code that renders the RdRp explorer makes 5 API calls, the info within them is redundant and it could definitely be simplified to one (or two at most) API calls.

Ideally:

• For each view on the frontend, there should be a corresponding API route that returns all the data needed to render it.
• API routes should be simple to understand and use, /path and a list of SRA ids.
• API routes should correspond directly to database tables or database views, this to simplify the whole data model and also to let the backend take care of most of the pre-processing needed (w/ appropriate indexes and caching).