Post-processing reactions, testing, benchmarking

[miguelmaso]

Main changes

• Deprecated Cauchy(cons_model, uh,..., Ω, dΩ...)
• Added Cauchy(cons_model, uh...)
• Added interpolate_L2_tensor(Ω, dΩ,...)

Those changes ease the task of computing reactions at a sub-domain.

Additional changes

• Added examples folder
• Added visco-elastic test using simulation from examples folder
• Updated visco-elastic benchmark using simulation from examples folder

EDIT:
Not needed the changes related to the Cauchy evaluation and interpolation. It's possible to directly integrate over gamma.

[github-actions]

Benchmark Results (Julia v1)

Time benchmarks

	main	62f9260...	main / 62f9260...
Constitutive models/Visco-elastic Ψ	0.0478 ± 0.028 ms	0.0475 ± 0.028 ms	1.01 ± 0.83
Constitutive models/Visco-elastic ∂Ψu	0.0609 ± 0.0052 ms	0.0605 ± 0.0052 ms	1.01 ± 0.12
Constitutive models/Visco-elastic ∂Ψuu	0.108 ± 0.024 ms	0.109 ± 0.018 ms	0.988 ± 0.27
Simulations/ViscoElastic	25.2 s	25 s	1.01
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	2.26 ± 0.042 s	2.24 ± 0.029 s	1.01 ± 0.023

Memory benchmarks

	main	62f9260...	main / 62f9260...
Constitutive models/Visco-elastic Ψ	1.24 k allocs: 0.0782 MB	1.24 k allocs: 0.0782 MB	1
Constitutive models/Visco-elastic ∂Ψu	1.36 k allocs: 0.0904 MB	1.36 k allocs: 0.0904 MB	1
Constitutive models/Visco-elastic ∂Ψuu	2.31 k allocs: 0.155 MB	2.31 k allocs: 0.155 MB	1
Simulations/ViscoElastic	0.369 G allocs: 28.9 GB	0.369 G allocs: 28.9 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	0.151 k allocs: 11.5 kB	0.151 k allocs: 11.5 kB	1

[miguelmaso]

@jmartfrut ready to merge

Simulation tests are running faster: