MDL-53327 search: add missing pluginfo lang strings

AMOS BEGIN
 CPY [searchengine,admin],[type_search,plugin]
AMOS END

lang/en/plugin.php

@@ -159,6 +159,8 @@
 $string['type_report_plural'] = 'Reports';
 $string['type_repository'] = 'Repository';
 $string['type_repository_plural'] = 'Repositories';
+$string['type_search'] = 'Search engine';
+$string['type_search_plural'] = 'Search engines';
 $string['type_theme'] = 'Theme';
 $string['type_theme_plural'] = 'Themes';
 $string['type_tool'] = 'Admin tool';