Upgrade EUI to 7.1.0

[chandlerprall]

Summary

Upgrade EUI from 7.0.0 -> 7.1.0

• Added append prop to EuiFieldText (#1567)
• Adjusted set of Elastic Logos in EuiIcon to look better in dark mode. (#1462)
• Added isCopyable prop to EuiCodeBlock (#1556)
• Added optional Snippet tab to docs and renamed demo tabs (#1556)
• Expanded getSecureRelForTarget to handle elastic.co domains as a referrer whitelist (#1565)
• New url utility for verifying if a URL is a referrer whitelist (#1565)
• Add iconSize to ButtonIcon type definition (#1568)

cc @mattkime

Checklist

Use strikethroughs to remove checklist items you don't feel are applicable to this PR.

- [ ] This was checked for cross-browser compatibility, including a check against IE11
- [ ] Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
- [ ] Documentation was added for features that require explanation or tutorials
- [ ] Unit or functional tests were updated or added to match the most common scenarios
- [ ] This was checked for keyboard-only and screenreader accessibility

For maintainers

• This was checked for breaking API changes and was labeled appropriately
  - [ ] This includes a feature addition or change that requires a release note and was labeled appropriately

[joelgriffith]

LGTM!

[elasticmachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request

[styxxxx4u]

Ruby