Add image glyph to EuiIcon

[andreadelrio]

Summary

As requested in #2844

Note: Some files I didn't directly edit have been updated. I'm guessing this is a result of running yarn compile-icons

Fixes #2844

Checklist

- [ ] Check against all themes for compatibility in both light and dark modes
- [ ] Checked in mobile
- [ ] Checked in IE11 and Firefox

• Props have proper autodocs
• Added documentation examples
• Added or updated jest tests
  - [ ] Checked for breaking changes and labeled appropriately
  - [ ] Checked for accessibility including keyboard-only and screenreader modes
• A changelog entry exists and is marked appropriately

[cchaos]

@andreadelrio Can you share a screenshot with the pixel grid?

[cchaos]

Also, when I look at the screenshot of the icon next to the others, this one feels a bit too bold. Usually we reserve filled areas for smaller portions like the folded corner of a page or a small circle with a plus. What if the mountains were outlines that reached all the way to the frame edges and just left the sun filled in?

[andreadelrio]

@andreadelrio Can you share a screenshot with the pixel grid?

Also, when I look at the screenshot of the icon next to the others, this one feels a bit too bold. Usually we reserve filled areas for smaller portions like the folded corner of a page or a small circle with a plus. What if the mountains were outlines that reached all the way to the frame edges and just left the sun filled in?

I was playing a bit with this idea. See:

I also noticed the version with filled mountains felt a bit off but couldn't quite put my finger on why...I think it looks a bit too "crowded" specially when used at 16px size .

[andreadelrio]

After taking feedback, the new icon looks like this:

[cchaos]

I think the outline for the mountains works a lot better. 🎉 👍

[ryankeairns]

Thanks @andreadelrio !!