Add alarm emergency response

[mxgrey]

This PR subscribes to the emergency topic so the full control robots can respond appropriately when an alarm is triggered.

[FloodShao]

Tested in office.world.
The following actions are performed:

1. Send loop request to robots
2. After the robots started moving, trigger the active alarm checkbox in the nav graph.
3. The two magnis will stop and returned to the nearest waypoint that marked as "is_parking_spot".
   Most of the parking spots have a name on it in the nav graph except one:

- [814.828, 239.25, 0, "", {is_parking_spot: [4, true]}]

The robot once stopped at a non-named waypoint, and that waypoint is this non-named parking_spot.

The emergency_response should works as intended.

[FloodShao]

The PR works as intended.

[FloodShao]

Tested in office.world.
The following actions are performed:

Send loop request to robots
After the robots started moving, trigger the active alarm checkbox in the nav graph.
The two magnis will stop and returned to the nearest waypoint that marked as "is_parking_spot".
Most of the parking spots have a name on it in the nav graph except one:

• [814.828, 239.25, 0, "", {is_parking_spot: [4, true]}]
  The robot once stopped at a non-named waypoint, and that waypoint is this non-named parking_spot.

The emergency_response should works as intended.