[feed] Added Channel for link to feed item; Updated rome library to version 1.15 (#8893)

* Added Channel for link to latest feed; update rome deoendency to version 1.15
* Removed unsed interface
* Run spotless

Signed-off-by: Christoph Weitkamp <github@christophweitkamp.de>

itests/org.openhab.binding.feed.tests/pom.xml

@@ -16,6 +16,8 @@
 
   <properties>
     <org.osgi.service.http.port>9090</org.osgi.service.http.port>
+    
+    <rome.version>1.15.0</rome.version>
   </properties>
 
   <dependencies>
@@ -27,7 +29,7 @@
     <dependency>
       <groupId>com.rometools</groupId>
       <artifactId>rome</artifactId>
-      <version>1.12.0</version>
+      <version>${rome.version}</version>
     </dependency>
     <dependency>
       <groupId>org.apache.servicemix.bundles</groupId>