refactor(performance-metrics): separate storage logic from tracker

[DerekMaggio]

Overview

Closes https://opentrons.atlassian.net/browse/EXEC-415

• Pulls out storage logic from tracker into MetricsStore object
• Defines MetricsMetadata to store information about the MetricsStore object

Test Plan

• Modified file storage test in performance-metrics to use the new classes.
  • Loads file content and validates it
• Modified test_track_analysis test in api/test_cli
  • Loads file content and validates it

Changelog

• Create MetricsMetadata in shared data which defines where to store data, what to call it, and the headers
• Create MetricsStore which handles creating any necessary directories or files and then storing data to the files
• Remove storage logic from RobotContextTracker then instantiate MetricsStore and call to its methods to handle data storage

Review requests

None

Risk assessment

Low