Add babel-plugin-styled-components to webpack config

[patrykkopycinski]

Summary

Plugin will improve debugging experience of styled-components

before:

after:

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

[patrykkopycinski]

@elasticmachine merge upstream

[elasticmachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: 0becff4

History

• 💔 Build #15060 failed 08eb4ef

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@elasticmachine merge upstream

[spalger]

LGTM, tested the performance impact this might have on the optimizer and it doesn't seem to have any noticeable impact.

[patrykkopycinski]

Thank you @spalger 💪