Update Ruler to use upstream Prom Rule Manager

[jtlisi]

This PR is a refactor of #1532 to utilize the Prometheus Rule Manager to schedule and evaluate rule groups.

Overview

• Utilize the upstream prometheus manager to scheduler and evaluate rules
• Sync and map rules from an external service (configdb) to a temporary file which is synced with the users prometheus rules manager
• Utilize afero to map rule files to allow for mocked tests using in memory filesystems and potentially using an in-memory file system in production if upstream changes can be made
• Utilize a protobuf interchange format for rules to allow for the effectively have a versionable format for storing and communicating rules

Affects:
#477
#493