Adapt UserSession

- Move from App methods to UserSession methods
- Deprecate corresponding App methods

src/Core/Session/Model/UserSession.php

@@ -24,6 +24,7 @@ namespace Friendica\Core\Session\Model;
 use Friendica\Core\Session\Capability\IHandleSessions;
 use Friendica\Core\Session\Capability\IHandleUserSessions;
 use Friendica\Model\Contact;
+use Friendica\Model\User;
 
 /**
  * This class handles user sessions, which is directly extended from regular session
@@ -50,6 +51,16 @@ class UserSession implements IHandleUserSessions
 		return false;
 	}
 
+	/** {@inheritDoc} */
+	public function getLocalUserNickname()
+	{
+		if ($this->isAuthenticated()) {
+			return $this->session->get('nickname');
+		}
+
+		return false;
+	}
+
 	/** {@inheritDoc} */
 	public function getPublicContactId()
 	{
@@ -122,6 +133,12 @@ class UserSession implements IHandleUserSessions
 		return $this->session->get('authenticated', false);
 	}
 
+	/** {@inheritDoc} */
+	public function isSiteAdmin(): bool
+	{
+		return User::isSiteAdmin($this->getLocalUserId());
+	}
+
 	/** {@inheritDoc} */
 	public function setVisitorsContacts()
 	{