#7468758 i18n: Localize EmptyContent component

Proposed Changes

• Localize EmptyContent component and translate fallback title.

Testing Instructions

• Change UI to a Mag-16 language.
• Checkout branch locally or use calypso.live build.
• Go to /posts/scheduled and confirm fallback title renders. Since it’s a new string, it’s likely to still be untranslated.
• Confirm EmptyContent component won’t render the fallback title if an empty string is passed as a prop value. For example:
  • Go to /domains/add/ and select a site.
  • Remove the value from the search field (if any) and confirm the EmptyContent component renders without the title.
• Confirm custom title prop renders as expected, e.g./posts/trashed/{domains}, /posts/scheduled/{domains}.

Pre-merge Checklist

• Have you written new tests for your changes?
• Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• Have you checked for TypeScript, React or other console errors?
• Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• Have we added the “[Status] String Freeze” label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?

Related to 472-gh-Automattic/i18n-issues