Adds the Gent2D constitutive model

[jmartfrut]

Implements the Gent2D hyperelastic constitutive model for 2D simulations.

This commit introduces the Gent2D model, including its energy function and derivatives, and adds a corresponding test case to ensure its correct behavior.

[github-actions]

Benchmark Results (Julia v1)

Time benchmarks

	main	602992b...	main / 602992b...
Constitutive models/Visco-elastic Ψ	0.0506 ± 0.027 ms	0.051 ± 0.027 ms	0.991 ± 0.75
Constitutive models/Visco-elastic ∂Ψu	0.0656 ± 0.0078 ms	0.0663 ± 0.0069 ms	0.99 ± 0.16
Constitutive models/Visco-elastic ∂Ψuu	0.114 ± 0.015 ms	0.118 ± 0.016 ms	0.967 ± 0.18
Simulations/StaticMechanicalDirichlet	0.145 ± 0.012 s	0.135 ± 0.0087 s	1.08 ± 0.11
Simulations/StaticMechanicalNeumann	0.132 ± 0.011 s	0.129 ± 0.012 s	1.02 ± 0.12
Simulations/ViscoElastic	21.4 s	20.8 s	1.03
Tensor algebra/Cofactor	0.07 ± 0.01 μs	0.07 ± 0.01 μs	1 ± 0.2
Tensor algebra/Det(A)Inv(A')	0.13 ± 0.01 μs	0.14 ± 0.01 μs	0.929 ± 0.097
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 ± 0.028 s	2.45 ± 0.043 s	1.02 ± 0.021

Memory benchmarks

	main	602992b...	main / 602992b...
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	1.36 k allocs: 0.0898 MB	1.36 k allocs: 0.0898 MB	1
Constitutive models/Visco-elastic ∂Ψuu	2.32 k allocs: 0.155 MB	2.32 k allocs: 0.155 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	0.343 G allocs: 22 GB	0.343 G allocs: 22 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