QQC2 TextEditor example uses deprecated API

{{
/home/craig/Projects/qt5/qtdeclarative/examples/quickcontrols2/texteditor/documenthandler.cpp: In member function ‘void DocumentHandler::setFontFamily(const QString&)’:
/home/craig/Projects/qt5/qtdeclarative/examples/quickcontrols2/texteditor/documenthandler.cpp:147:32: warning: ‘void QTextCharFormat::setFontFamily(const QString&)’ is deprecated: Use setFontFamilies instead [-Wdeprecated-declarations]
147 | format.setFontFamily(family);
}}

As the example basically mirrors the API, this might require a slightly larger refactoring to use the recommended setFontFamilies.