Write a generalized search API for optimized ORM

 - make our ORM models reflect the new underlying database schema
 - generalize the Onionoo API to use SQLALchemy primitives
 - (re)write a subset of Onionoo query filters for the API
 - make all additional parts (e.g. query_info) work with the new ORM
 - write a simplistic relay status entry list lookup API point for ext.testing