Conditionally launch sub8/sub9 usb_to_can driver based on sub launched

[cbrxyz]

What needs to change?

The can.launch file should be able to launch either driver, depending on which sub we want to launch.

How would this task be tested?

1. Launch both subs and ensure that the appropriate driver is launched at the same time.

Contacts

• [ ] We need help from the mechanical team.
• [ ] We need help from the electrical team.
• [ ] We need help from Dr. Schwartz or other faculty.
• [ ] We need help from a company or an organization.
• [ ] We need help from another UF staff member or organization (ex, facilities).