Enable tests for boot2qt

The tests for boot2qt were disabled with commit
b9bfe241

. The tests can
be enabled since qtdeclarative now fallbacks to software
renderer if OpenGL is not supported.

Two changes were needed to pass tests on boot2qt
1. Add option to disable tests requiring WAV format and use
that in the boot2qt environment
2. Skip some tst_QPainterVideoSurface tests if GLContext is
not supported by the platform

Task-number: QTBUG-60268
Change-Id: I236207fedb505124a2c7edf0caccd85011ab1416
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>