SECURITY: Fix RevDel log entry information leaks

DELETED_ACTION is supposed to hide the target of the log entry. But a
few places weren't doing this properly.

This fixes:
* API list=logevents no longer returns the pageid when the target is
  hidden.
* Enhanced RecentChanges no longer includes the log target page in the
  CSS class. This should also make the CSS class actually useful.
* Watchlist no longer shows log entries with DELETED_ACTION unless the
  user has deletedhistory, and with SUPPRESSED_ACTION unless the user
  has suppressrevision.

Bug: 58699
Change-Id: I57f13bfc970a33ffd5a399ffb450d9ed0b77902f