Force the number of quadrature points to 1 in some constitutive models

Describe the issue
For multiphase poromechanics simulations on hexahedral meshes, the memory requirements of the constitutive models (multifluid, relperm, capillary pressure) are huge because of the way we determine the number of quadrature points in these models

Proposed cleanup
Does anyone mind if I do the following:

• Force the number of quadrature points in the fluid, relperm, capillary pressure models to 1 (as already done for permeability and conductivity)
• Modify the poromechanics kernels accordingly

?

I did not find another way to do it (for instance, using mesh levels and discretization) given the way poromechanics kernels interact with the mesh levels.

@rrsettgast @CusiniM @klevzoff @castelletto1