packagegroup-qt5-qtcreator-debug: Add package group

This allow for easy installation of needed packages for remote
debugging using QtCreator. The qtdeclarative-plugins package provides
the needed infrastructure to remotely debug QML application.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Tested-by: Giulian Vivan <giulian@ossystems.com.br>
populate_sdk_qt5.bbclass: Add support for qtcreator-debug

This adds a new image feature for easier remote debugging with
QtCreator.

The qtcreator-debug needs to be added as a valid item for image
features and having it inside the populate_sdk_qt5 is too late. User
will see a parser error as OE-Core images does not inherit the classs.
The possible workaround for it is to include it inside layer.conf file
until a kind of "bbclassappend" support is in place.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Tested-by: Giulian Vivan <giulian@ossystems.com.br>