[RT-2860] Introduce dependent steps in the exploit file

[blu3r4y]

Acceptance Criteria:

• By default, steps can be executed in arbitrary order
• However, if the "needs" are set for a step, that step can only be run if the listed prior steps executed with a non-zero exit code

Tasks:

• Adapt the exploit file and update the docs
• In the backend, store the exit codes of each individual step and let steps only run when its prior steps executed successfully
• Provide an endpoint to the frontend "can_run_step" that checks this precondition
• In the frontend, before enabling the button, perform the "can_run_step" check
• Use this new syntax for the CMDi exploit