ECMS-5427: UIDocumentNodeList encounters NPE for linked node

Fix description:
  - use WCMCoreUtils to get LinkManager service in LinkUtils.java, check if real node of NodeLinkAware object exists in UIDocumentNodeList.gtmpl
ECMS-5686: IE - XSS on 'select relation' - Content Management

Fix description:
  -  the title of content is already unescaped. Remove the code to unescape the content
ECMS-5750: Enable DMS Structure should not display by default for all user

Fix description:
  - We just display option enable DMS structure if current user is admin user.
ECMS-5749: The layout of Site Explorer will be broken when contains a crash file

Fix description:
  - Not allow to display "Delete" button if current node is mandatory of parent node.
ECMS-5767: [Security] DDoS vulnerability with /rest/fckconnector/jcr/uploadFile/upload/ service

Fix description:
 - allow only non anonymous user to call FCKCoreRESTConnector methods
ECMS-5563: CLONE - Impossibility to publish content without having the right of delete

Fix description:
   - ManagePublicationAction does not require Remove permission. So remove CanRemoveNodeFilter from this component
   - Do not authorize remove operation when storing a node in CmsServiceImpl
ECMS-5672: User indentity not found while rendering group drives in UIDrivesArea

Fix description:
  - Verify the validity of the value to avoid access null value
ECMS-5759: XSS in Site Explorer/New Content/CSS File

Fix description:
  -Remove options=noSanitization in the dialog template of CSS file to not allow input java script into the content field.
Merge commit '09e87ac7103e29dedd1a296fd90967377d5fec48' into HEAD