Replace qtextscriptengine's font tar-ball with open source fonts

Some of the tst_qtextscriptengine.cpp tests (in qtbase/tests/auto/gui/text/qtextscriptengine/) are suppressed unless certain fonts are installed; one has to set QT_HAVE_TEST_FONTS=1 in the environment to enable the tests. Allegedly we used to have a tar-ball of the needed fonts, that folk could install to make that viable, but we don't have the right to redistribute it and it's not clear if we even still have it.

These days there are open-source fonts that can probably be used to make all of that redundant – include them in a data directory, package them in a qrc and arrange for them to be available to our font-engine from there, for example. This would make our text-rendering tests more consistent across platforms and less hassle for folk to actually do.