Integration Tests for MacOS

[tegefaulkes]

Specification

This issue is to track the progress of PKG integration tests for the Mac build.

A selection of bin tests need to be updated to support using the mac executable as the target for testing.

The main tests that need to be updated in order are;

1. bin/agent/start.test.ts
2. bin/bootstrap.test.ts
3. rest of bin/agent
4. bin/polykey.test.ts

Additional context

• Related Fix Failing Build Tests on Windows & MacOS #14

Tasks

1. spec this out some more