Build with qt6 and cmake

First build with qt6 and cmake.
QET compil, but a lot of things don't work.
Build tested on debian sid and ubuntu 25.04.

Dependency needed under debian and ubuntu :
qtcreator cmake qt6-tools-dev qt6-svg-dev libsqlite3-dev
libkf6coreaddons-dev extra-cmake-modules libkf6widgetsaddons-dev

sources/ElementsCollection/elementslocation.cpp

@@ -807,13 +807,13 @@ bool ElementsLocation::setXml(const QDomDocument &xml_document) const
 			QString			   path_ = collectionPath(false);
 			QRegularExpression rx("^(.*)/(.*\\.elmt)$");
 
-			if (rx.exactMatch(path_))
+			if (auto regex_match = rx.match(path_); regex_match.hasMatch())
 			{
 				return project()
 					->embeddedElementCollection()
 					->addElementDefinition(
-						rx.cap(1),
-						rx.cap(2),
+						regex_match.captured(1),
+						regex_match.captured(2),
 						xml_document.documentElement());
 			}
 			else