frontend: Alerter mini-widget: Colour-code messages by severity

[Michael-F-Bryan]

Current behaviour

It'd be nice if the MAVLINK message logs displayed at the top of the cockpit UI were colour-coded based on the log severity. This would act as a quick visual indicator of something being wrong and supplement the existing text on the right-hand side of the log message.

For example, you might have the "CRITICAL" and "EMERGENCY" as red, "WARNING" as yellow, and so on.

Expected or desired behaviour

(imagine the red boxes are actually coloured in)

Prerequisites

• I have checked to make sure that a similar request has not already been filed or fixed.