MDL-51261 admin: Fix the heading when displaying all plugins

Not directly related to the issue but spotted while developing it and it
is not worth of submitting in a separate issue.

At the Plugins check page, when the "Display the full list of installed
plugins" link was followed, the heading at the next page read something
like "Number of plugins requiring your attention: 357". That is
misleading as this is actually not the number of displayed plugins, not
the number of plugins requiring attention.

admin/renderer.php

@@ -999,13 +999,14 @@ public function plugins_check_table(core_plugin_manager $pluginman, $version, ar
 
         } else {
             $out  = $this->output->container_start('somehighlighted', 'plugins-check-info');
-            $out .= $this->output->heading(get_string('somehighlighted', 'core_plugin', $sumofhighlighted));
             if (empty($options['full'])) {
-                $out .= html_writer::link(new moodle_url('/admin/index.php',
+                $out .= $this->output->heading(get_string('somehighlighted', 'core_plugin', $sumofhighlighted));
+                $out .= html_writer::link(new moodle_url($this->page->url,
                     array('confirmupgrade' => 1, 'confirmrelease' => 1, 'showallplugins' => 1, 'cache' => 0)),
                     get_string('somehighlightedinfo', 'core_plugin'));
             } else {
-                $out .= html_writer::link(new moodle_url('/admin/index.php',
+                $out .= $this->output->heading(get_string('somehighlightedall', 'core_plugin', $sumofhighlighted));
+                $out .= html_writer::link(new moodle_url($this->page->url,
                     array('confirmupgrade' => 1, 'confirmrelease' => 1, 'showallplugins' => 0, 'cache' => 0)),
                     get_string('somehighlightedonly', 'core_plugin'));
             }

lang/en/plugin.php

@@ -72,6 +72,7 @@
 $string['rootdir'] = 'Directory';
 $string['settings'] = 'Settings';
 $string['somehighlighted'] = 'Number of plugins requiring your attention: {$a}';
+$string['somehighlightedall'] = 'Number of installed plugins: {$a}';
 $string['somehighlightedinfo'] = 'Display the full list of installed plugins';
 $string['somehighlightedonly'] = 'Display only plugins requiring your attention';
 $string['source'] = 'Source';