[Vectorizer] Extend fpmin/fpmax tests to test semantic variants

This extends the test cases in argmin-argmax-fp to test for the semantic
variants of fpmin/fpmax operations. This test will now also cover
fpminimum/fpmaximum and fpminimum_num/fpmaximum_num.

Change-Id: I33b4b63a3bec60d002a42e3fe14a1abda518d3b0