[EuiDataGrid] Add sorting icon if the column is sorted

[stratoula]

Summary

It adds a sorting indicator on the EuiDataGridColumn which renders only when the column is sorted and indicates the sorting direction.

Checklist

• Check against all themes for compatibility in both light and dark modes
• Checked in mobile
• Checked in Chrome, Safari and Firefox
• Checked Code Sandbox works for the any docs examples
• Added or updated jest tests

[stratoula]

I have used the sortUp and sortDown icons. I would appreciate a help here for design improvements.

[kibanamachine]

Preview documentation changes for this PR: https://eui.elastic.co/pr_4343/

[kibanamachine]

Preview documentation changes for this PR: https://eui.elastic.co/pr_4343/

[snide]

Added a minor PR to adjust some spacing. This is a nice PR with the appropriate tests.

I tested it extensively in browser in a couple scenarios. The truncation still works as I'd expect when the column is collapsed.

[kibanamachine]

Preview documentation changes for this PR: https://eui.elastic.co/pr_4343/

[kertal]

🎉 from Discover side!

[kibanamachine]

Preview documentation changes for this PR: https://eui.elastic.co/pr_4343/

[snide]

@stratoula Don't forget a changelog before you merge this.

[stratoula]

@snide thank you, I def missed that 🙂

[cchaos]

@stratoula disregard my last comment. Apparently it's more of a contentious change than I thought 😆

[kibanamachine]

Preview documentation changes for this PR: https://eui.elastic.co/pr_4343/

[snide]

OK. @cchaos and I discussed. This is safe to merge as-is (upon @chandlerprall approval). We'll revisit the sorting arrows more generically in EUI (since tables use them) in a later PR.

[kibanamachine]

Preview documentation changes for this PR: https://eui.elastic.co/pr_4343/

[chandlerprall]

Changes LGTM; tested various configurations in the PR's published docs.

Thanks for the test coverage!