search: rename query_converter.go to query/helpers.go
Created by: rvantonder
Stacked on https://github.com/sourcegraph/sourcegraph/pull/34671.
This leaves two functions UnionRegExps
and LangToFileRegexp
in query_converter.go
which are basically query helpers used all over the code base, e.g.,
So I don't know that there's a nicer place for them to live than query/helpers.go
(maybe query/converters.go
?) If you have a better suggestion lmk.
Test plan
Semantics-preserving.