LPS-35937 Read description

Hey Brian,

I have sent the pull as you suggested with SessionMessages and without using PortalUtil.addPortalMessage. I didn't include "requestProcessed" yet but I will include in next commits.

The issue with this approach of SessionMessages is that it won't work when used from external plugins (see https://github.com/brianchandotcom/liferay-plugins/pull/1639) because the session attributes are not shared between the portal and the plugin.

"requestProcessed" message works because it's consumed from portlet_messages.jspf and it has renderRequest

```java
(String)SessionMessages.get(renderRequest, "requestProcessed");
```

but we are using it from top_messages.jsp and we only have request there so we cannot retrieve the values of the session sent by an external portlet.

```java
GetterUtil.getString(SessionMessages.get(request, SessionMessages.KEY_PORTAL_MESSAGES_JSP_PATH))
```

Should we use LIFERAY_SHARED attributes as in here https://github.com/sergiogonzalez/liferay-portal/commit/b708c0011217aa010e3c904db0529d673a80d2e7 ?