MDL-77313 restore: re-add field to indicate course/category search.

When the two restore forms for searching courses and categories were
converted to core templates in eb9935c9 they lost the named submit
button, which broke searching.

backup/util/ui/renderer.php

@@ -786,6 +786,10 @@ class core_backup_renderer extends plugin_renderer_base {
             'extraclasses' => 'rcs-search mb-3 w-25',
             'inputname' => restore_course_search::$VAR_SEARCH,
             'searchstring' => get_string('searchcourses'),
+            'buttonattributes' => [
+                (object) ['key' => 'name', 'value' => 'searchcourses'],
+                (object) ['key' => 'value', 'value' => 1],
+            ],
             'query' => $component->get_search(),
         ];
         $output .= $this->output->render_from_template('core/search_input', $data);
@@ -955,6 +959,10 @@ class core_backup_renderer extends plugin_renderer_base {
             'extraclasses' => 'rcs-search mb-3 w-25',
             'inputname' => restore_category_search::$VAR_SEARCH,
             'searchstring' => get_string('searchcoursecategories'),
+            'buttonattributes' => [
+                (object) ['key' => 'name', 'value' => 'searchcourses'],
+                (object) ['key' => 'value', 'value' => 1],
+            ],
             'query' => $component->get_search(),
         ];
         $output .= $this->output->render_from_template('core/search_input', $data);

lib/templates/search_input.mustache

@@ -28,6 +28,12 @@
         "searchstring": "Search settings",
         "value": "policy",
         "btnclass": "primary",
+        "buttonattributes": [
+            {
+                "key": "name",
+                "value": "hello"
+            }
+        ],
         "query": "themedesigner",
         "hiddenfields": [
             {
@@ -59,7 +65,10 @@
            value="{{ query }}"
         >
         <div class="input-group-append">
-            <button type="submit" class="btn {{^btnclass}}btn-submit{{/btnclass}} {{ btnclass }} search-icon">
+            <button type="submit"
+                class="btn {{^btnclass}}btn-submit{{/btnclass}} {{ btnclass }} search-icon"
+                {{#buttonattributes}}{{ key }}="{{ value }}" {{/buttonattributes}}
+            >
                 {{#pix}} a/search, core {{/pix}}
                 <span class="sr-only">{{ searchstring }}</span>
             </button>