Make Tester check shapes of reference and model output (#7589)

Make Tester check shapes of ref and model output

torch.allclose() will broadcast data if neccessary. This means that
Tester.run_method_and_compare_outputs() may pass even though a delegate
produced an output of wrong shape.


Change-Id: If62907e0fc69cc28b1f5ce5f8cfd6f31b1870a1e

Signed-off-by: Oscar Andersson <oscar.andersson@arm.com>