Follow up to https://github.com/discourse/discourse/pull/41795
This adds content-localization support for manually created links in the
built-in Community sidebar section.
Built-in Community links like Topics, My posts, Review, Admin, etc.
still use their existing frontend i18n labels and do not expose
localization controls. Only admin-created links in the Community section
can be localized (since only the admin can edit it).
The earlier PR had skipped adding these entirely for the Community
section