search: generate Zoekt query using method on Basic query
Created by: rvantonder
More prep for removing pattern info. First I need to absorb the query_converter.go
file into jobs. This PR moves the function that generates Zoekt queries to be a method on Basic query.
query_converter.go
has always been a holding ground for "messy" query conversion. It entangles a lot of concerns: converting queries to PatternInfo and also PatternInfo to Zoekt queries. We don't want to route through PatternInfo type, we want that type gone.
Test plan
Semantics-preserving.