Need an option to tell the user what the default arguments for a test are

Lava-test currently supports overriding the options passed to a test, but lacks the ability to show the user the current defaults. We should add this information somewhere in the test. One possibility is that we simply add a lava-test info command to show information about a test. This could also grow into something like showing a short summary of what the test does in addition to the command line defaults.