Simplifies Dirichlet boundary condition definition

[jmartfrut]

Removes now-unnecessary time-dependent evolution functions from the Dirichlet boundary condition definition, leading to a more concise and readable implementation.

[github-actions]

Benchmark Results (Julia v1)

Time benchmarks

	main	257a07a...	main / 257a07a...
Constitutive models/Visco-elastic Ψ	0.0479 ± 0.027 ms	0.0479 ± 0.027 ms	0.999 ± 0.8
Constitutive models/Visco-elastic ∂Ψu	0.0625 ± 0.002 ms	0.0625 ± 0.002 ms	1 ± 0.045
Constitutive models/Visco-elastic ∂Ψuu	0.111 ± 0.015 ms	0.112 ± 0.015 ms	0.993 ± 0.19
Simulations/StaticMechanicalDirichlet	0.137 ± 0.008 s	0.135 ± 0.0083 s	1.01 ± 0.086
Simulations/StaticMechanicalNeumann	0.134 ± 0.012 s	0.132 ± 0.012 s	1.01 ± 0.13
Simulations/ViscoElastic	21 s	21.1 s	0.991
Tensor algebra/Cofactor	0.07 ± 0.01 μs	0.069 ± 0.01 μs	1.01 ± 0.21
Tensor algebra/Det(A)Inv(A')	0.13 ± 0.01 μs	0.13 ± 0.001 μs	1 ± 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	2.54 ± 0.019 s	2.56 ± 0.021 s	0.994 ± 0.011

Memory benchmarks

	main	257a07a...	main / 257a07a...
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