Feature/raw cargo opts

[bazaah]

Adds a parameter 'test_args_raw' that allows users to pass raw args/options to cargo/libtest.

It also refactors how conditional checks are handled: rather than checking all combinations of bools for each endpoint, it builds up a variable, which is passed to cargo test. This makes the logic easier to extend and reason about.

Finally, the various eq / ne conditionals have their syntax altered:

• Changed 'true' (string) => true (bool)
• Swapped arg positions so the correct type coercion occurs