Add automated test for "Restore A Page"

The manual test is here: Restore A Page

Existing automated coverage

• RecycleBinIT#restore: as superadmin, creates a page with content, deletes it, clicks Restore on the delete outcome page and asserts title and content are restored
• RecycleBinIT#deletedDocumentIsRestricted: as superadmin, after deletion navigates to the page URL and restores it from the deleted pages entry Actions
• RecycleBinIT#viewDeletedPage: navigating to a deleted page shows the Deleter; the non-admin deleter has the Restore action available but never clicks it
• DeletePageIT#deleteWithoutNewTarget: asserts "The requested page could not be found." and the Deleter on the delete outcome page

Missing automated coverage

• As a simple user with delete right, create P1 with content and delete it
• Navigate to P1 and assert "The requested page could not be found.", the Deleter and a Deletion Date (add a DeletedPageEntry getter for the date)
• Click Restore in the Actions column as that same user and assert P1 is restored with its previous content

Suggested location: xwiki-platform-core/xwiki-platform-flamingo/xwiki-platform-flamingo-skin/xwiki-platform-flamingo-skin-test/xwiki-platform-flamingo-skin-test-docker/src/test/it/org/xwiki/flamingo/test/docker/RecycleBinIT.java

Found by comparing the XWiki 18.4.4 manual test runs against the automated tests on master (a0055f10a1a).