[NET_HANDLER] Runtime status

[benliao1]

Currently, Runtime has no way of communicating to Dawn or Shepherd what the robot's status is. This information would be very useful for students (using Dawn) and staff (using Shepherd) to know, without having to call a member of Runtime over to ssh into the robot and open the shared memory UI.

This should be implemented using a new protobuf, defined in the protos repo, and should contain the following information:

• Runtime version
• Dawn connection status
• Shepherd connection status
• Battery voltage
• Run mode

This message shall be sent on the following conditions:

• When x number of seconds has passed since the last Runtime status message was sent to this client (we should determine an appropriate x ... probably 10 or 30 seconds?)
• When Dawn or Shepherd connects or disconnects
• When the run mode changes

The message shall be sent to all currently active clients, i.e. if Shepherd sends a run mode change to Runtime, Runtime should immediately send a Runtime status message to both Dawn and Shepherd confirming that it has indeed changed into the new run mode.

Resolving this issue will also resolve #208 and #209 .

[BrandonWong14]

We could also add whether to replace the battery or not to the list if things that need to be sent in runtime status.