fix: fix using wrong index in from_csv_row

[DerekMaggio]

Overview

I accidentally specified the same index multiple times when hardcoding from_csv_row.

Since hardcoding in this case is a no-no fix it by using built-in dataclass methods to look up headers and converting to/from csv.

Test Plan

• Added unit tests that fail before fix was implemented due to hard coding
• Added unit tests that ensure ordering of converted data. Although this tests the dataclass package more than it is testing our software, it is still helpful to have this because the docs aren't super clear about if the order is maintained

Changelog

• Create a CSVStorageBase dataclass that contains shared methods
• Have RawActivityData and ProcessResourceUsageSnapshot inherit from CSVStorageBase

Review requests

Is it weird having a blank dataclass as a base? I was having trouble when trying to use an ABC.

Risk assessment

The lowest of lows

[sfoster1]

lgtm!