WP-CLI: Test Edge Cases

[mjangda]

• Build a custom command that runs of out of memory to see what the experience is like and how we should improve it.
• Build a custom command that takes a long time to test the same thing.
• Two people running the same command.
• One person running the same command in two windows.
• Excessive CPU usage.
• Excessive disk usage - download a large file.
• Excessive disk utilization (IO).
• Fatal error.
• Non zero exit code.
• Cancelling a command (Ctrl-C) on Windows