implement shooter

[danielbrownmsm]

Summary The flywheel shooter code from last year needs to be ported to C++. hardware:

• falcon 500 shooter motor for the flywheel
• neo 550 indexer motor

sensors:

• IR proximity sensor (DigitalInput) at the top to stop the ball
• built-in falcon 500 encoder (could just use the built-in closed loop control, or run a PID on the RIO)
• built-in neo 550 encoder, though we don't need it

Work Required

• port shooter subsystem code from last year
• port shooter commands from last year (can be deferred to a later issue)
• write unit tests for the shooter subsystem

Verification

• CI passes
• code documented
• shooter code has same functionality as the Java version