Set QT_QML_GENERATE_QMLLS_INI for the project when generateQmllsIniFiles is selected

Qt Creator has for some time under the Preferences -> Language Client -> QML Language Server had the option to "Create .qmlls.ini files for new projects". This does the job and creates the .qmlls.ini files where necessary. However when moving a project to another machine or user, the .qmlls.ini files are not checked in to git and then if the other machine or user does not have this checked, the .qmlls.ini files are no longer generated according to the new location's build locations etc and so the code model may no longer work as expected. To ensure this doesn't happen, one can add

set(QT_QML_GENERATE_QMLLS_INI ON)

to the top level CMakeLists.txt file.

It would be great if Qt Creator added this line to the generated CMakeLists.txt file when creating new projects based on the check box as described, and having CMake run the tool as prescribed explicitly, rather than somewhat relying on the check box being set on target machines and hoping QtCreator implicitly runs the tool for you. Note, that when adding new QML Modules or libraries to the project using a file based operations the .qmlls.ini isn't created by QtCreator - only a CMake instruction will do this.