Create autotest to ensure that every module has appropriate (L)GPL and FDL license files

Create an autotest (similar to the license header autotest) to check that each module has copies of the qtbase/LICENSE.* and qtbase/LGPL_EXCEPTION.txt files if the module has any files with the matching license nominated in the QT_BEGIN_LICENSE marker.

Further details can be found in the email thread titled "[Development] Qt modules missing mandatory LICENSE files" and the commit https://codereview.qt-project.org/#change,47236