Initial port to Qt6

CMakeLists.txt

lang/CMakeLists.txt

src/CMakeLists.txt

src/charts/tbarchartdelegate.cpp

src/charts/tbarchartdelegate.h

src/charts/tchartitem.h

src/charts/tcharttipitem.h

src/dialogs/tdialogloaderobject.cpp

src/dialogs/tlevelcreatoritem.h

src/dialogs/tlevelselector.h

src/dialogs/tmelgenitem.h

src/libs/core/CMakeLists.txt

src/libs/core/exam/tqaunit.cpp

src/libs/core/instruments/tguitarbg.cpp

src/libs/core/instruments/tguitarbg.h

src/libs/core/instruments/tpianobg.cpp

src/libs/core/instruments/tpianobg.h

src/libs/core/score/taddnoteitem.h

src/libs/core/score/tnoteitem.h

src/libs/core/score/tscoreobject.h