Added Staggered Test

[miguelmaso]

must be merged before #137

[miguelmaso]

FYI @jmartfrut

[github-actions]

Benchmark Results (Julia v1)

Time benchmarks

	main	ec807dd...	main / ec807dd...
Constitutive models/Visco-elastic Ψ	0.0486 ± 0.035 ms	0.0496 ± 0.034 ms	0.98 ± 0.98
Constitutive models/Visco-elastic ∂Ψu	0.0547 ± 0.0025 ms	0.0555 ± 0.0034 ms	0.984 ± 0.075
Constitutive models/Visco-elastic ∂Ψuu	0.103 ± 0.013 ms	0.104 ± 0.017 ms	0.99 ± 0.2
Simulations/StaticMechanicalDirichlet	0.144 ± 0.0083 s	0.142 ± 0.014 s	1.01 ± 0.11
Simulations/StaticMechanicalNeumann	0.139 ± 0.013 s	0.134 ± 0.018 s	1.04 ± 0.17
Simulations/ViscoElastic	19.3 s	19 s	1.01
Tensor algebra/Cofactor	0.07 ± 0 μs	0.07 ± 0.001 μs	1 ± 0.014
Tensor algebra/Det(A)Inv(A')	0.13 ± 0.01 μs	0.13 ± 0.011 μs	1 ± 0.11
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	2.86 ± 0.017 s	2.83 ± 0.018 s	1.01 ± 0.0089

Memory benchmarks

	main	ec807dd...	main / ec807dd...
Constitutive models/Visco-elastic Ψ	1.24 k allocs: 0.0777 MB	1.24 k allocs: 0.0777 MB	1
Constitutive models/Visco-elastic ∂Ψu	1.29 k allocs: 0.0826 MB	1.29 k allocs: 0.0826 MB	1
Constitutive models/Visco-elastic ∂Ψuu	2.25 k allocs: 0.149 MB	2.25 k allocs: 0.149 MB	1
Simulations/StaticMechanicalDirichlet	1.51 M allocs: 0.109 GB	1.51 M allocs: 0.109 GB	1
Simulations/StaticMechanicalNeumann	1.48 M allocs: 0.0933 GB	1.48 M allocs: 0.0933 GB	1
Simulations/ViscoElastic	0.326 G allocs: 20.5 GB	0.326 G allocs: 20.5 GB	1
Tensor algebra/Cofactor	1 allocs: 0.0781 kB	1 allocs: 0.0781 kB	1
Tensor algebra/Det(A)Inv(A')	4 allocs: 0.25 kB	4 allocs: 0.25 kB	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