Add an unlink glyph to EuiIcon

[ThomThomson]

In adding the unlink from visualize library action to embeddable panels, I realized that EuiIcon glyph collection has a link icon, but no unlink icon.

This could also be used for unlink from saved search.

Something similar to this icon from fontawesome:

[elizabetdev]

@ThomThomson thanks for suggesting this icon.

I started working on this issue. I tried to create an icon that would match the link icon. So in case, we would click from link to unlink it would look it's being transformed from one to another.

I did some tests here:
https://codesandbox.io/s/silly-ramanujan-tpsjo?file=/index.js

@chaos do you think one of these options would work?

[cchaos]

Can you paste the screenshots of these at 100% zoom level to see how they look at their actual 16x16 size?

[elizabetdev]

@chaos, you can also see them here already transformed into react components: https://codesandbox.io/s/silly-ramanujan-tpsjo?file=/index.js.

[cchaos]

My main thought is that they all still look very similar to the original link icon. Using the slash could still be interpreted as the connector of the two links. I would try to make it more dissimilar / make the break more pronounced.

[elizabetdev]

@chaos what do you think of one of these two (3 and 4)?

[cchaos]

I'm diggin the last one because it gives movement to the original, especially when used together in a toggle button. And it's a little more unique than the quintessential one from the PR summary.

[ThomThomson]

@miukimiu, #4 looks great!

[elizabetdev]

Thanks for the feedback. I'm going to open a PR with the last option.