Enable package search

I came to Stackage to search for `split`, as it's referred to in a `.cabal` file. But I get a list of results which don't seem to be ordered; a list of functions named `split` from various packages:

Search will return the module only if I already know it's namespaced module name:

And now, the search engine results seem to be ordered for relevance.

Summary
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1. Facilitate package name searches either by ranking them high in relevance or displaying them parallel to function searches.
2. Use package name match as a component of relevance generally.

I'm happy to help implement these.