Respect user machine settings

[myasonik]

Describe the feature:
Kibana should respect user machine settings such as color scheme and animation using media queries such as prefers-color-scheme and prefers-reduced-motion.

The changes that this would cause inside Kibana is already done (advanced settings for theme and disabling are already available) so the work required would be minimal to support this.

Has an added boon of acting as a pseudo-user settings — users setup their machines how they want. When they go to Kibana, Kibana "just works" the same way the rest of their machine does.

Describe a specific use case for the feature:

As a user, I prefer a dark theme on a computer because it strains my eyes less. I have setup my machine to prefer a dark theme across the OS.

Kibana should continue to respect those settings.

[elasticmachine]

Pinging @elastic/kibana-core-ui (Team:Core UI)

[elasticmachine]

Pinging @elastic/kibana-design (Team:Design)

[afgomez]

Working on this as part of my space-time