Add event system / architecture

[e5h]

Functionality partially exists with the messaging system. There are a few different tasks running concurrently, and they all have unique state machines which should be influenced by the idea of "events" generating from other tasks.

Example:

1. Device task detects "wifi button" held, generates a "wifi button held" event
2. Network task receives "wifi button held" event, attempts to connect to wifi as sta
3. Network task detects successful connection, generates a "wifi sta connected" event
4. Device task should receive a "wifi sta connected" event, and toggle the "wifi LED"
5. Display task can indicate a wifi connection event (?)