Slew for Turns, Swings, and other subsystems

[Unionjackjz1]

Slew currently only works on drive. It should work for turns and swings. Slew should also have an independent function, such as pid_drive_set_slew() where it called pid_drive_set(x, x, true).

Slew might have to be revamped to make this happen and turned into a class. It could also be exposed to the user easier too, and examples could exist for how to implement it for other subsystems, like a lift or intake.