New alert messages

[aaronchongth]

New feature implementation

Implemented feature

New messages that allow custom interactions to arise from the robots, fleets or other parts of the system, namely alerts, notifications, user interactions, etc

• Alert
• AlertParameter
• AlertResponse

Example usage

This can hopefully extend to many more cases, other than these 3 examples provided

Case 1

• Fleet adapters with custom perform_actions will require user input or responses for certain decisions, can publish an alert with all the possible responses listed
• API server picks it up and prompts the users on the frontend
• User chooses a response
• API server will publish the response back down to the fleet adapter

Case 2

• Fleet adapters wishes to inform users something has happened in the form of a notification (info,warning or error), with no user response required

Case 3

• Fleet adapters with custom perform_actions will require input or responses from other parts of the system (non-human), an alert can be sent out with it toggled not to be displayed
• The other system can respond using the response message as well

[xiyuoh]

LGTM, have tested it and it is comprehensive enough to contain the different types of information we would need to publish messages between the fleet adapter and RMF web.

[xiyuoh]

LGTM