Added tests for themal laws

[miguelmaso]

Added some tests for thermal laws

[github-actions]

Benchmark Results (Julia v1)

Time benchmarks

	main	8dc8eda...	main / 8dc8eda...
Constitutive models/Visco-elastic Ψ	0.0473 ± 0.032 ms	0.0481 ± 0.034 ms	0.984 ± 0.97
Constitutive models/Visco-elastic ∂Ψu	0.0541 ± 0.0019 ms	0.0544 ± 0.0019 ms	0.994 ± 0.049
Constitutive models/Visco-elastic ∂Ψuu	0.101 ± 0.015 ms	0.101 ± 0.015 ms	0.997 ± 0.2
Simulations/StaticMechanicalDirichlet	0.132 ± 0.0064 s	0.134 ± 0.0079 s	0.984 ± 0.075
Simulations/StaticMechanicalNeumann	0.128 ± 0.014 s	0.129 ± 0.013 s	0.993 ± 0.14
Simulations/ViscoElastic	18.4 s	18.3 s	1
Tensor algebra/Cofactor	0.07 ± 0.01 μs	0.061 ± 0.01 μs	1.15 ± 0.25
Tensor algebra/Det(A)Inv(A')	0.131 ± 0.01 μs	0.13 ± 0.001 μs	1.01 ± 0.077
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	2.67 ± 0.013 s	2.72 ± 0.02 s	0.983 ± 0.0087

Memory benchmarks

	main	8dc8eda...	main / 8dc8eda...
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: 0.108 GB	1.51 M allocs: 0.108 GB	1
Simulations/StaticMechanicalNeumann	1.48 M allocs: 0.093 GB	1.48 M allocs: 0.093 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