Fixed L2 projection

[miguelmaso]

Using the default Gridap operator · will cover all the possible tensor operations

[github-actions]

Benchmark Results (Julia v1)

Time benchmarks

	main	01b98a5...	main / 01b98a5...
Constitutive models/Visco-elastic Ψ	25.6 ± 17 μs	25.1 ± 17 μs	1.02 ± 0.97
Constitutive models/Visco-elastic ∂Ψu	0.0318 ± 0.0021 ms	31 ± 1.8 μs	1.03 ± 0.09
Constitutive models/Visco-elastic ∂Ψuu	0.0608 ± 0.031 ms	0.0602 ± 0.031 ms	1.01 ± 0.73
Simulations/StaticMechanicalDirichlet	0.132 ± 0.0066 s	0.134 ± 0.0071 s	0.984 ± 0.072
Simulations/StaticMechanicalNeumann	0.129 ± 0.011 s	0.13 ± 0.012 s	0.991 ± 0.12
Simulations/ViscoElastic	12.1 s	11.9 s	1.02
Tensor algebra/Cofactor	0.06 ± 0.01 μs	0.061 ± 0.01 μs	0.984 ± 0.23
Tensor algebra/Det(A)Inv(A')	0.11 ± 0.001 μs	0.111 ± 0.01 μs	0.991 ± 0.09
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	2.77 ± 0.011 s	2.76 ± 0.017 s	1.01 ± 0.0075

Memory benchmarks

	main	01b98a5...	main / 01b98a5...
Constitutive models/Visco-elastic Ψ	0.542 k allocs: 0.0443 MB	0.542 k allocs: 0.0443 MB	1
Constitutive models/Visco-elastic ∂Ψu	0.593 k allocs: 0.0492 MB	0.593 k allocs: 0.0492 MB	1
Constitutive models/Visco-elastic ∂Ψuu	1.02 k allocs: 0.0839 MB	1.02 k allocs: 0.0839 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: 0.0927 GB	1.48 M allocs: 0.0927 GB	1
Simulations/ViscoElastic	0.162 G allocs: 12.7 GB	0.162 G allocs: 12.7 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