typeahead: Update for email_address_visibility settings.

This commit changes the code to show user according to emails based
on email_address_visibilty_values and the type of user.

1. email_address_visibility = admins,members and guests

   Typeaheads are shown according to original emails.

2. email_address_visibility = admins only

   Typeaheads are shown according to original email to admins which
   were previously shown according to system-generated email of
   form "user10@zulipdev.com".

   For non-admins, typeaheads are not shown according to emails as
   they are not visible in the typeahead itself to non-admins.

3. email_address_visibility = nobody

   Typeaheads are not shown according to emails for all type of users.

frontend_tests/node_tests/composebox_typeahead.js

@@ -13,6 +13,7 @@ zrequire('compose_pm_pill');
 zrequire('composebox_typeahead');
 zrequire('recent_senders');
 zrequire('settings_org');
+const settings_config = zrequire('settings_config');
 set_global('md5', function (s) {
     return 'md5-' + s;
 });
@@ -695,6 +696,15 @@ run_test('initialize', () => {
         assert.equal(matcher(query, othello), false);
         assert.equal(matcher(query, cordelia), false);
 
+        query = 'oth';
+        page_params.realm_email_address_visibility =
+            settings_config.email_address_visibility_values.admins_only.code;
+        page_params.is_admin = false;
+        assert.equal(matcher(query, deactivated_user), false);
+
+        page_params.is_admin = true;
+        assert.equal(matcher(query, deactivated_user), true);
+
         function sorter(query, people) {
             return typeahead_helper.sort_recipients(
                 people,

frontend_tests/node_tests/settings_user_groups.js

@@ -9,6 +9,7 @@ const noop = function () {};
 const pills = {
     pill: {},
 };
+const settings_config = zrequire('settings_config');
 
 let create_item_handler;
 
@@ -119,6 +120,10 @@ run_test('populate_user_groups', () => {
         return [realm_user_group];
     };
 
+    people.get_visible_email = function () {
+        return bob.email;
+    };
+
     let templates_render_called = false;
     const fake_rendered_temp = $.create('fake_admin_user_group_list_template_rendered');
     global.stub_templates(function (template, args) {
@@ -199,6 +204,10 @@ run_test('populate_user_groups', () => {
             query: 'ali',
         };
 
+        const fake_context_for_email = {
+            query: 'am',
+        };
+
         (function test_source() {
             const result = config.source.call(fake_context, iago);
             const emails = result.map(user => user.email).sort();
@@ -213,6 +222,16 @@ run_test('populate_user_groups', () => {
 
             result = config.matcher.call(fake_context, alice);
             assert(result);
+
+            page_params.realm_email_address_visibility =
+                settings_config.email_address_visibility_values.admins_only.code;
+            page_params.is_admin = false;
+            result = config.matcher.call(fake_context_for_email, bob);
+            assert(!result);
+
+            page_params.is_admin = true;
+            result = config.matcher.call(fake_context_for_email, bob);
+            assert(result);
         }());
 
         (function test_sorter() {