Visco and anisotropy multiple dispatch

[miguelmaso]

This PR is a draft. I want to make easier the weak forms, I'd like there were agnostic with respect to the constitutive model, the only dispatch is the phyisics: mechano, electro, thermo

[github-actions]

Benchmark Results (Julia v1)

Time benchmarks

	main	a6810f9...	main / a6810f9...
Constitutive models/Visco-elastic Ψ	0.0496 ± 0.03 ms	0.0491 ± 0.028 ms	1.01 ± 0.84
Constitutive models/Visco-elastic ∂Ψu	0.0652 ± 0.0063 ms	0.0642 ± 0.011 ms	1.01 ± 0.2
Constitutive models/Visco-elastic ∂Ψuu	0.114 ± 0.017 ms	0.112 ± 0.016 ms	1.02 ± 0.21
Simulations/StaticMechanicalDirichlet	0.158 ± 0.01 s	0.16 ± 0.012 s	0.989 ± 0.1
Simulations/StaticMechanicalNeumann	0.192 ± 0.0098 s	0.192 ± 0.0085 s	0.996 ± 0.067
Simulations/ViscoElastic	8.24 s	8.27 s	0.996
Tensor algebra/δδ_λ_2d	30 ± 0 ns	30 ± 0 ns	1 ± 0
Tensor algebra/δδ_μ_2d	30 ± 0 ns	30 ± 0 ns	1 ± 0
time_to_load	2.5 ± 0.019 s	2.5 ± 0.012 s	1 ± 0.0091

Memory benchmarks

	main	a6810f9...	main / a6810f9...
Constitutive models/Visco-elastic Ψ	1.25 k allocs: 0.0794 MB	1.25 k allocs: 0.0794 MB	1
Constitutive models/Visco-elastic ∂Ψu	1.37 k allocs: 0.0917 MB	1.37 k allocs: 0.0917 MB	1
Constitutive models/Visco-elastic ∂Ψuu	2.31 k allocs: 0.158 MB	2.31 k allocs: 0.158 MB	1
Simulations/StaticMechanicalDirichlet	1.7 M allocs: 0.118 GB	1.7 M allocs: 0.118 GB	1
Simulations/StaticMechanicalNeumann	2.19 M allocs: 0.14 GB	2.19 M allocs: 0.14 GB	1
Simulations/ViscoElastic	0.127 G allocs: 8.28 GB	0.127 G allocs: 8.28 GB	1
Tensor algebra/δδ_λ_2d	0 allocs: 0 B	0 allocs: 0 B
Tensor algebra/δδ_μ_2d	0 allocs: 0 B	0 allocs: 0 B
time_to_load	0.149 k allocs: 11.1 kB	0.149 k allocs: 11.1 kB	1

[miguelmaso]

@jmartfrut ready to be reviewed

[miguelmaso]

It's not 100% needed to merge this constribution, but it can be useful for inspiration.

After implementing this, I've come to two conclusions:

• The order of passing arguments to the weak form/constitutive model should be: 1) degrees of freedom, 2) variables
• We should have a brainstorming and discuss towards a clear definition of the structures reflecting the scientific definitions: physics, kinematics, constitutive model, weak form, etc.