Add test notification tool (#28334)

* Add test notification tool

* Add frontend styles

* Remove option from admin view

* Refactor create post and add translations

* Fix several CI errors

* Fix API and frontend snapshots

* Refactor trailing and leading icon on buttons

* Add different button states

* i18n-extract

* Fix wrong text

* Add tests

* Fix wrong string

* Fix test

* feat: E2E send test notifications (#28371)

* Refactor send desktop notification

* Address rest of the feedback

* Fix tests

* Add correct link

* Fix test

---------

Co-authored-by: Mattermost Build <build@mattermost.com>
Co-authored-by: yasserfaraazkhan <attitude3cena.yf@gmail.com>

webapp/platform/client/src/client4.ts

@@ -3292,6 +3292,13 @@ export default class Client4 {
         );
     };
 
+    sendTestNotificaiton = () => {
+        return this.doFetch<StatusOK>(
+            `${this.getBaseRoute()}/notifications/test`,
+            {method: 'post'},
+        );
+    };
+
     testEmail = (config?: AdminConfig) => {
         return this.doFetch<StatusOK>(
             `${this.getBaseRoute()}/email/test`,