settings: Fix save-discard widget fo.

The save-discard widget was not showing and hiding correctly
for the "Automated messages and emails" section in organization
settings panel. This was because the "proposed_val" was always
being returned as "undefined" for language setting as
"data-language-code", which is used to check the proposed value
of setting, was not set after changes in 36475daba7.
This commit fixes it by passing language_code value to
language_selection_widget and thus setting "data-language-code"
attribute correctly.

The changes in 36475daba7 removed language_code parameter from
language_selection_widget as it was not passed in the template
from "Display settings" section. So, this commit also passes
the language_code parameter to language_selection_widget from
"Display settings" section.
This change sets the "data-language-code" attribute even when
it is not being used there, to make sure there is no reference
to undefined fields in language_selection_widget.

Note that the above bug was reproducible only if you have not
changed the language even once and are trying to change the
other settings, as the data-language-code attribute was set
after selecting a language from the modal, but it was not
set initially after rendering the page.

web/src/settings.js

@@ -110,6 +110,7 @@ export function build_page() {
         user_can_change_email: settings_data.user_can_change_email(),
         user_role_text: people.get_user_type(page_params.user_id),
         default_language_name: settings_display.user_default_language_name,
+        default_language: user_settings.default_language,
         realm_push_notifications_enabled: page_params.realm_push_notifications_enabled,
         settings_object: user_settings,
         send_read_receipts_tooltip: $t({

web/src/settings_display.js

@@ -95,6 +95,10 @@ function user_default_language_modal_post_render() {
             $("#user-preferences .language_selection_widget .language_selection_button span").text(
                 new_language,
             );
+            $("#user-preferences .language_selection_widget .language_selection_button span").attr(
+                "data-language-code",
+                setting_value,
+            );
 
             change_display_setting(
                 data,

web/templates/settings/display_settings.hbs

@@ -10,7 +10,8 @@
             {{> language_selection_widget
               section_name="default_language_name"
               setting_value=default_language_name
-              section_title=settings_label.default_language_settings_label }}
+              section_title=settings_label.default_language_settings_label
+              language_code=default_language }}
         {{/unless}}
 
         <div class="input-group">

web/templates/settings/language_selection_widget.hbs

@@ -6,7 +6,7 @@
         {{/if}}
     </label>
     <button type="button" class="language_selection_button button rounded small" data-section="{{section_name}}">
-        <span class="{{section_name}}">{{setting_value}}</span>
+        <span class="{{section_name}}" data-language-code="{{language_code}}">{{setting_value}}</span>
         <i class="fa fa-pencil"></i>
     </button>
 </div>