GUACAMOLE-2139: Add automatic retrieval of license information where absent. Remove unused license info.

doc/licenses/cas-client/NOTICE

@@ -2,8 +2,10 @@
 # URL:     https://www.apereo.org/projects/cas
 # From:    'Apereo Foundation' (https://www.apereo.org/)
 # License: Apache v2.0
+# Source:  https://raw.githubusercontent.com/apereo/java-cas-client/refs/tags/v${VERSION}/cas-client-core/NOTICE
+# Source:  https://raw.githubusercontent.com/apereo/java-cas-client/refs/tags/cas-client-${VERSION}/cas-client-core/NOTICE
 #
-# --- BEGIN LICENSE FILE ---
+# --- BEGIN LICENSE FILE [3.6.4] ---
 This project includes:
   Jasig CAS Client for Java - Core under Apache License Version 2.0
-# --- END LICENSE FILE ---
+# --- END LICENSE FILE [3.6.4] ---