XWIKI-10535: When fully replacing existing document WikiStream instance output module should not generate delete event

* Fix failing test (HTML validation).

- fix jacoco

- revert some changes in the XWikiCachingRightService that broke backward compatibility of PR checking.

- Increase specificity

- Map for legacy elements that use .secondary class

* mvn xar:format

- added rules for the other button style classes

* put back in the extra filter until XWIKI-10384 is resolved
  afterwards this commit can be reverted

* fix jacoco failure

* a few related improvements:
** added support for skin/baseskin in context, request and xwiki.cfg
** make xhtml/1.0 the default raw.syntax
** introduce internal template script service
** introduce internal template macro

- input border color;
- navbar-tab active border color.

* Add support for embedding attachments located in the template document when "includeTemplateAttachments" = true

XWiki-6456: Sending a mail from a Template should check rights on the document which is being used as a template

* Fixed bug

* Moved interface to internal for now
* Moved all template-related code to a template package

+ Added missing @Unstable

XWIKI-10510: Add ability to send emails from a Template document containing a XWiki.Mail xobject

* Fixed functional test

* Tune the API by removing the no parameter constructor (I'm still hesitating but it seems better)

XWIKI-10507: Introduce a mechanism for Mail API extenders to generate pre-filled MimeMessage objects
* Improve API