* Enhance ticket merge feature

- Moved logic into a separate function
- Added ability to merge tasks and actors
- Added ability to change link type
- Added ability to specify if the process stop after a single failure, or if it tries merging all tickets and rollback individual ones that fail. Not exposed in UI but usable through API or plugins.
- Added tests for merging tickets

closes #3139

add validation comment to timeline item
fix rights and dark theme colors

Bumps [tecnickcom/tcpdf](https://github.com/tecnickcom/TCPDF) from 6.2.26 to 6.3.2.
- [Release notes](https://github.com/tecnickcom/TCPDF/releases)
- [Changelog](https://github.com/tecnickcom/TCPDF/blob/master/CHANGELOG.TXT)
- [Commits](https://github.com/tecnickcom/TCPDF/compare/6.2.26...6.3.2

)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

if the column is a reserved word of SQL, the query fails

Signed-off-by: Thierry Bugier <tbugier@teclib.com>

* Add relevant massive actions on main form

* ui/ux for navigation header

hide dropdown when no actions remaining
confirm transfer action
Limit documents list (at least) to current entity
stronger title

* add icons to single actions

* Missing global

* move design to a single 'actions' buttton and polish UI

* plural for massiveactions

* fix for review

* Try to get rid of empty IN from transfer; closes #6243

* Update inc/transfer.class.php

Co-Authored-By: Alexandre Delaunay <delaunay.alexandre@gmail.com>

* Update inc/transfer.class.php

Co-Authored-By: Alexandre Delaunay <delaunay.alexandre@gmail.com>

* Update inc/transfer.class.php

Co-Authored-By: Alexandre Delaunay <delaunay.alexandre@gmail.com>

* feat: add code to itilcategories

* feat(test): add unit test

* [fixup] Fix typo in code

Closes #5809

Prevent circular relations
closes #2226