XWIKI-14735: The Dashboard page disappears from Applications Panel when a simple user adds attachments or Edits the page

* Decrease a bit the TPC (I only removed code from the DashboardMacro and I didn't expect the TCP to decrease.. with less code to test and the same amount of unit tests the TCP should increase or at least stay the same..)

* Use CKEditor's Macro Wizard for selecting and editing dashboard gadgets.

* Increase TPC a bit...

* The gadget transformations are executed (since XWIKI-13816) before the code that checks if a gadget is based on a rendering macro, so we need to look for MacroMarkerBlock instead.

XWIKI-9583: After deactivating the Message Stream, the title of the {{messageSender /}} macro is still visible
* Not needed anymore now that the Dashboard macro doesn't display the gadget if the content is empty

* Improved design

XWIKI-9583: After deactivating the Message Stream, the title of the {{messageSender /}} macro is still visible

XWIKI-10118:     XWIKI-10118  Container macro cannot be added more than once with different number of columns

Fix tests in xwiki-platform-dashboard-macro to reflect CSS class changes

XWIKI-13613: XWikiContext should automatically bridge old "vcontext" property to execution context one
XWIKI-13614: Allow setting a binding in Velocity macro and access it a following JSR223 script macro
XWIKI-13558: Velocity and general script contexts are not always in sync

This reverts commit 239f5eb2.

This reverts commit 9e5dadc4.

- Removing the Welcome gadget + fixing the other gadgets order