Nav2 Docking: Add Option for Reversing into Dock

[SteveMacenski]

Currently, we detect the dock and use the vision control loop to drive into the dock. If you have sensors in the back, you can set the staging pose to reversed & dock_backwards to dock. If you do not have sensors in back, there should be an option to dock_backwards but stage forward, thus needs:

• Detect dock
• Rotate to 180 deg heading
• Reverse into the dock (without updates to detected pose)

We'd just need to add the option for that 180 maneuver