Improving EuiIcon a11y

[miukimiu]

Summary

Closes #579

When PR #2554 was merged we couldn't use aria-labelledby because the SVGR at that time didn't allow to specify an id for the title tag.

After requesting a new SVGR feature to allow a title id, it was finally merged.

This PR updates the package @svgr/core to the latest version so we can specify a title id to use with the aria-labelledby. Some logic was changed and icons were generated again to include the new SVGR feature.

The other task remaining on #579, translating the icon names, doesn't make sense anymore because we are not using the icon name as a default title.

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

[chandlerprall]

Nice! Changes LGTM; logic looks correct, additional test is great, and spot checked a couple of the generated icon files.

[snide]

Ran locally and checked the code and the output of the SVGs.