The first commit optimizes getting the list of all package names, by removing the highly inefficient toPackageNames and instead creating allPackageNames which uses the keys of a map instead of the values that toPackageNames was iterating over. This commit also introduces use of this new function in places where this is all we need.

The second commit optimizes the browse listing (i.e. not search), which was doing n map lookups using makeItemList, where n is the total amount of packages. This is now avoided by simply fetching pre-made PackageItems using getAllLists. The speedup may not be large since the construction of these PackageItems using makeItemList was already used in the search feature, and this branch wasn't reported to be slow.

Tested on my local Hackage instance, but not benchmarked properly yet.