feat(pages): put provided pages in a specific classpath directory (#338)

That directory will be read by the engine. It will avoid having to declare each page individually

Relates to [RUNTIME-183](https://bonitasoft.atlassian.net/browse/RUNTIME-183)

bonita-war/pom.xml

@@ -383,7 +383,7 @@
                                     <destFileName>page-admin-user-details.zip</destFileName>
                                 </artifactItem>
                             </artifactItems>
-                            <outputDirectory>${folder_frontend_web_resources}/WEB-INF/classes</outputDirectory>
+                            <outputDirectory>${folder_frontend_web_resources}/WEB-INF/classes/org/bonitasoft/web/page</outputDirectory>
                         </configuration>
                     </execution>
                 </executions>