XWIKI-11940: Make internal the classes and interfaces of the LESS Module that should not have been public and refactor bad designed code.

* Fix checkstyle.

* Using StringUtils instead of the "Not Invented Here" syndrom.

XWIKI-11940: Make internal the classes and interfaces of the LESS Module that should not have been public and refactor bad designed code
* bulletproofing

XWIKI-11941: Outdated extension step is enabled if some installed extension is invalid on another wiki

XWIKI-11940: Make internal the classes and interfaces of the LESS Module that should not have been public and refactor bad designed code.

* Fix the problem for Windows. File.getParent() did not work because we use "/" as file separator.

XWIKI-11939: Automatically remember login and passord of the current user to reuse it with REST based tools
* fix bug

XWIKI-11939: Automatically remember login and passord of the current user to reuse it with REST based tools

[Misc] Fix bug noticed by Sonar (Impossible cast) + improved the tests and removed some unnecessary checks

* execute xar:format twice because of it's license related bug

* update test

* index raw value only for short text

XWIKI-11926: Improve the document diff UI in order to reuse it to show the differences between multiple documents
* Use a non-breaking space at the start of context (unmodified) lines so that they are correctly aligned even when spaces are not preserved (because we want the lines to wrap).

WIKI-11926: Improve the document diff UI in order to reuse it to show the differences between multiple documents
* Add/Update page objects.

* give more time to solr indexer

* more flexible behavior

* yes finally fixed that test

* qf take short fields names and not full fields names

XWIKI-8760: Fail to display DBTree property in edit mode when an item from the third selected column does not appear in the first column
* Added a test about the presence of the parent in the first column, this way we can push the node in the tree in a way which will not cause a javascript error

* Better test

* refactor based on XWIKI-11932

* Apply Denis' suggestions: better javadoc and simplified function

[Misc] Move the setUp in the test since there's only one method (and there should be only one method in functional tests in general)

* fix javadoc

* This fix add methods to get rid of the XWikiGroupService's cache which is not up to date on some race condition.
* So the UserBridge now calls the XWikiGroupService without using the cache.
* And the Security Cache has now its own way to retrieve the groups of a user, to avoid calling the bridge too often.

* bulletproofing

* Fix typo, add the @Unstable annotation and some comments. Thanks Enygma2002 and vmassol.

XWIKI-11926: Improve the document diff UI in order to reuse it to show the differences between multiple documents
XWIKI-9785: If attachment is of type 'text' (js, css, txt, etc.) allow the user to enable the diff across history

XWIKI-11929: XWikiAttachment#getContentInputStream() returns the content for the latest version if the content is not already loaded

Fix the deprecated uses of @Component