New Windows Qt5/Qt6 CI test, enable -platform windows:fontengine=freetype add new .bat for Qt6 installer and portable version

misc/Lancer QET_qt6.bat

@@ -0,0 +1,12 @@
+@echo off
+
+rem Se rend dans le dossier qui convient
+set current_dir=%~dp0
+cd /d %current_dir%
+
+rem Met la collection QET en lecture seule
+attrib +r elements/* /S /D
+
+rem lance QElectroTech
+set command=bin\qelectrotech.exe --common-elements-dir=elements/ --common-tbt-dir=titleblocks/ --lang-dir=lang/ --config-dir=conf/ --data-dir=conf/  %*
+@start %command%