manage streams: Promote "Announce stream" in UI.

The option to announce streams is tied to whether
it's public or not, so it makes sense to move it
here.

static/js/stream_edit.js

@@ -478,6 +478,7 @@ export function initialize() {
         const stream = sub_store.get(stream_id);
 
         const template_data = {
+            ask_to_announce_stream: false,
             stream_privacy_policy_values: stream_data.stream_privacy_policy_values,
             stream_privacy_policy: stream_data.get_stream_privacy_policy(stream_id),
             stream_post_policy_values: stream_data.stream_post_policy_values,

static/js/stream_settings_ui.js

@@ -621,6 +621,7 @@ export function setup_page(callback) {
         // the user can create, by showing other options as disabled.
         const stream_privacy_policy = stream_data.stream_privacy_policy_values.public.code;
         const template_data = {
+            ask_to_announce_stream: true,
             can_create_streams:
                 settings_data.user_can_create_private_streams() ||
                 settings_data.user_can_create_public_streams() ||

static/templates/stream_settings/stream_creation_form.hbs

@@ -35,15 +35,6 @@
                       stream_post_policy=stream_post_policy_values.everyone.code
                       is_stream_edit=false }}
                 </div>
-
-                <div id="announce-new-stream">
-                    <label class="checkbox">
-                        <input type="checkbox" name="announce" value="announce" checked />
-                        <span></span>
-                        {{t "Announce stream" }}
-                    </label>
-                    <span class="fa fa-question-circle settings-info-icon" aria-hidden="true" id="announce-stream-docs"></span>
-                </div>
             </section>
             <section class="block">
                 <label class="stream-title" for="people_to_add">

static/templates/stream_settings/stream_types.hbs

@@ -13,6 +13,17 @@
     {{/each}}
 </div>
 
+{{#if ask_to_announce_stream}}
+    <div id="announce-new-stream">
+        <label class="checkbox">
+            <input type="checkbox" name="announce" value="announce" checked />
+            <span></span>
+            {{t "Announce stream" }}
+        </label>
+        <span class="fa fa-question-circle settings-info-icon" aria-hidden="true" id="announce-stream-docs"></span>
+    </div>
+{{/if}}
+
 <div class="input-group">
     <h4>{{t 'Who can post to the stream?'}}
         {{> ../help_link_widget link="/help/stream-sending-policy" }}