Testing: Enforce array as Lodash path argument

[aduth]

This pull request seeks to enforce a new custom ESLint rule encouraging the use of an array as the second parameter of Lodash functions accepting a "path" (e.g. _.get). The intent here is to skip a parsing step to convert a string path to its array equivalent, which occurs internally in Lodash (source).

The performance impact is not as bad as I had suspected for simple strings, as the internal logic tests for properties, skipping the parse for use like _.get( foo, 'bar' ). Further, its stringToPath is memoized so only calculated once. All the same, this rule encourages consistency, avoids any such regular expression testing, avoids memory overhead of memoization, and avoids the string ever needing to be parsed.

Testing instructions:

There should be no behavior impact of these changes.

Ensure tests pass:

npm test