(SUP-3472) Add file sync storage metric collection

[jarretlavallee]

Prior to this change, the filesync storage metrics were excluded in all
cases, so there was no way to determine the timing of the filesync
storage operations. This change adds in three metrics for the filesync
storage service to measure the commits, pre-commit, and add-rm times.

[puppet-community-rangefinder]

puppet_metrics_collector::service::puppetserver is a class

that may have no external impact to Forge modules.

This module is declared in 0 of 579 indexed public Puppetfiles.

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Exact matches are those that we can positively identify via namespace and the declaring modules' metadata. Non-namespaced items, such as Puppet 3.x functions, will always be reported as near matches only.