[Iga] Testing behaviour problem

[roigcarlo]

Description

Currently almost half of the CPP tests from the IGA depend on a Constitutive law from the Structural app:

[  SKIPPED ] KratosIgaFastSuite.IgaShell3pElementP3
[  SKIPPED ] KratosIgaFastSuite.IgaShell3pElementP4
[  SKIPPED ] KratosIgaFastSuite.IgaShell3pElementP5
[  SKIPPED ] KratosIgaFastSuite.IgaShell3pElementP3Disp
[  SKIPPED ] KratosIgaFastSuite.IgaShell3pElementP4Disp
[  SKIPPED ] KratosIgaFastSuite.IgaShell3pElementP5Disp
[  SKIPPED ] KratosIgaFastSuite.IgaShell3pElementP4Scordelis
[  SKIPPED ] KratosIgaFastSuite.IgaShell3pElementP5Scordeli

In order to be able to activate those tests again we have three options:

1. Since tests are not unitest but behaviour check, move the tests to python.
2. Add a compile time dependency in the testing binary to the structural
3. Add a compile time dependency in the KratosIgaCore to the Structural app

1 Would be my preferred solution.
2 is currently impossible because both IGA and Structural define the same variables which cause double de-allocations when exiting.
3 Is possible but implies removing the above-mentioned variables and make IGA completely dependent on Structural.

Aside from the design perspective, I have no voice on this topic so please tell me what to do.

Ping @RiccardoRossi, @rickyaristio (i ping you because you are the online people with commits here still active)

[rickyaristio]

We do not intent to make IGA dependent to SMA. I will probably neglect option 3.

So, it seems that the first option is the best at this moment.