[Client] Add moderation tab with investigate, password reset, and avatar removal

- New Moderation tab: search a user to show account info, alternate
  accounts, login sessions, and staff last logins; actions to reset the
  user's password (shows the generated temporary password) and remove the
  user's avatar
- 'Investigate user' entry in the user context menu opens the tab pre-loaded
  for that user
- Warning dialog shows the infraction level of each warning category
- Tab wired into TabSupervisor with a moderator-gated menu action, shortcut,
  and tabs.ini persistence (default closed)

libcockatrice_settings/libcockatrice/settings/tabs_settings.cpp

@@ -101,6 +101,11 @@ bool TabsSettings::getTabReportOpen() const
     return getValue("report", QString(), QString(), false).toBool();
 }
 
+bool TabsSettings::getTabModerationOpen() const
+{
+    return getValue("moderation", QString(), QString(), false).toBool();
+}
+
 void TabsSettings::setTabVisualDeckStorageOpen(bool value)
 {
     setValue(value, "visualDeckStorage");
@@ -140,3 +145,8 @@ void TabsSettings::setTabReportOpen(bool value)
 {
     setValue(value, "report");
 }
+
+void TabsSettings::setTabModerationOpen(bool value)
+{
+    setValue(value, "moderation");
+}