Add automated test for "View Page Likes"

The manual test is here: View Page Likes

Existing automated coverage

• LikeIT#likeUnlikeDefaultConfiguration: Two users like the same page and the likers Live Data lists both, but it is opened directly by URL (?viewer=likers, LikersPage#goToLikers).

Missing automated coverage

• After two users like a page, open "More actions > Likes" and assert that the likers Live Data lists both users.
• Click the like-count link next to the Like button (.like-number a) and assert the same likers Live Data.
• Add page-object methods for both entry points (for example LikeButton#clickLikersLink and a ViewPage more-actions helper).

Suggested location: xwiki-platform-core/xwiki-platform-like/xwiki-platform-like-test/xwiki-platform-like-test-docker/src/test/it/org/xwiki/like/test/ui/LikeIT.java

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