[GeoMechanicsApplication] Make sure the structural/interface elements used in the quay wall work with the geo reset displacement process

[rfaasse]

This holds for the following elements:

• LinearTimoshenkoCurvedBeamElement2D3N
• LinearTimoshenkoBeamElement2D3N
• LinearTimoshenkoBeamElement2D2N
• TrussElement3D2N
• TrussElementLinear3D2N
• LinearTrussElement2D (two and three nodes, but this shouldn't add extra work)
• Our new interface element

This means we need to make sure:

• All elements can calculate the PK2_STRESS_VECTOR (does this make sense, or should the reset displacement process be able to handle different stresses?)
• Make sure their respective constitutive laws use the InitialState to calculate their material response
• Make sure these elements work with the 'rest' input, especially pay attention to 'rest' in combination with excavation