Reduce artifact discovery overhead

[jonathanj-square]

Motivated by this comment:
#2989 (comment)

The current approach involves iterating over repositories in a registry. This is identified by Stuart as being unscalable and slow in general. Instead access into the repository should be key driven. This may require some rethinking of how components in a release such as module compilation artifacts (single binary for Go, multiple jars for JVM), schemes, etc get linked together.