XWIKI-18836: Links located in macros are not saved as backlinks

  * Provide a new LinkParser component whose jobs is to allow extracting
    links from an XDOM
  * Improve MacroRefactoring role to allow extract links from a macro
    content or parameter
  * Improve DefaultMacroRefactoring to parse macro content for
    extracting links
  * Improve IncludeMacroRefactoring to extract links from macro
    parameters
  * Refactor XWikiDocument to rely on LinkParser
  * Improve existing integration test to check with various links to
    ensure backlinks are created in each case (standard link, default
macro link, nested macro link, image link, include macro parameter)

(cherry picked from commit eb7d809e)