Severity Names / Colors need clarity

[jtrack3d]

Is your feature request related to a problem? Please describe.
In the API documentation we have the limit evaluator's draft section. I understand it is a draft and thus I'd like to point out the inconsistencies in the current release.

https://github.com/nasa/openmct/blob/master/API.md#limit-evaluators-draft

It lists 5 colors: purple, red, orange, yellow, cyan. Order significance not provided.

In the Gauge control, the code gives precedence as Critical > Distress > Severe > Warning > Watch on how it chooses high/low (see my previous enhance request for details).

openmct/src/plugins/gauge/components/GaugeComponent.vue

Line 678 in b18aa48

updateLimits(telemetryLimit) {

Enhancement Request #7672

The example SinewaveLimitProvider, confuses things. It defines colors for these severities: getLimits defines Critical=Red, Distress=Orange, Severe=Purple, Warning=Yellow, Watch=Cyan. While it's getLimitEvaluator only handles yellow and red. From the defined variables, the value ranges is 2.2/Purple > 0.9/Red > 0.7/Orange > 0.5/Yellow > 0.45/Cyan. This is purple > red > orange whereas if the Gauge order (Critical>Distress>Severe) of names applies, it should be red > orange > purple?

openmct/example/generator/SinewaveLimitProvider.js

Line 23 in b18aa48

var PURPLE = {

Finally, to confuse things further, the CSS is-limit--yellow and is-limit--red both have icon indicators on them, but no other is-limit--colors have icons. When limits appear on tables, these icons appear. It implies red and yellow are the most severe because they add icons.

Describe the solution you'd like
For sanity, at a minimum, I'd like to see:

1. Define an order to severities in the documentation.
2. Associate a color to that severity and be consistent.
3. Icons should appear on all or only the most severe colors severities in the CSS.

For personal preference, in my mind:

1. Critical > Distress > Severe > Warning > Watch order makes sense.
2. Based on visible light spectrum wavelength, Red > Orange > Yellow > Cyan > Purple
3. Add an icon to Orange CSS (rather than remove from yellow).

With this preference, those that are using Red (Icon) > Yellow (Icon) are relatedly still consistent. My only angst is that the Cyan color in the CSS for limit is a much bolded color choice compared to the others as it is also used for Staleness indication. The other colors are less saturated. :)

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Notes: CCSDS only defines 4 severities:

1. Informational (not a severity as it is nominal)
2. Warning
3. Alarm
4. Severe
5. Criticial