Track Hiera lookups during compile

We want to start optionally keeping track of what Hiera lookups are used to compile a catalog for a node. This information is useful for more accurately determining whether changes to Hiera data will change the compiled catalog for a given node, as CD4PE does with Impact Analysis.

This epic tracks the work of instrumenting Puppet to gather that data, and then sending it along to PuppetDB. Note that it should be possible to trigger this collection for a specific compilation (e.g. with a parameter on a catalog request) rather than have it always on or always off.