Changes

[all] Replace tinyxml by external tinyxml2 (#4240)

* Replace tinyxml by external tinyxml2.

* Customize TinyXML2 cmake module to use a find _package or fetch content mechanism.

* Replace find or fetch mechanism by classical cmake find module.

* Fix missed cmake target name change

* Handle error if tinyxml2 package not found but required

* Fix compilation with Dump Visitor activated

* Install libtinyxml

* FIX error checking

* Actually fix...

* FIX error loading VTU xml files

* FIX scene test

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Co-authored-by: bakpaul <bakpaul@hotmail.fr>
Co-authored-by: Paul Baksic <30337881+bakpaul@users.noreply.github.com>