The message bar intent styles could be improved

When documenting the interaction service, I noticed that the message bar intent styles could be improved. Right now, there's little distinction between:

- Information and Confirmation (I think one just adds buttons)
- Error and Warning (only seem to differ by icon)

The colors for the dark theme aren't really fun to look at either.

#### Light theme

#### Dark theme

#### Possible considerations

Maybe the confirmation message bar could use some of the Aspire purple colors? The warning could be more orange, and maybe a blue for the information intent? There was also peer feedback about the action buttons feeling a bit distant from the words when there's fewer words—but personally, I think those are fine since they're next to the dismissal "X" button. But more contrast on those might help a bit.

#### API naming considerations

One final, somewhat related thought: when the team was talking about this UX element, we naturally referred to it as "notification bar", however; the API calls it a "message bar" which seems like a potential opportunity to improve that API name to more closely align with its use. When I first saw this API, I assumed "message bar" was like a "status bar" or something, near the footer. Then I saw what it did in the UI, and thought, "oh, that's a notification."