refactor: improve new array-form codegen

[AayushSabharwal]

Minor performance changes

[github-actions]

Benchmark Results (Julia vlts)

Time benchmarks

	master	56b2b30...	master / 56b2b30...
ODEProblem	6.42 ± 0.33 ms	6.83 ± 0.31 ms	0.94 ± 0.064
init	0.113 ± 0.03 ms	0.116 ± 0.033 ms	0.975 ± 0.38
large_parameter_init/ODEProblem	19.5 ± 1.9 ms	21.5 ± 0.91 ms	0.911 ± 0.095
large_parameter_init/init	0.11 ± 0.029 ms	0.111 ± 0.033 ms	0.987 ± 0.39
mtkcompile	11.1 ± 0.71 ms	12.1 ± 0.51 ms	0.913 ± 0.07
sparse_analytical_jacobian/ODEProblem	24 ± 1.2 ms	25.6 ± 0.92 ms	0.936 ± 0.056
sparse_analytical_jacobian/f_iip	0.071 ± 0.01 μs	0.07 ± 0 μs	1.01 ± 0.14
sparse_analytical_jacobian/f_oop	0.377 ± 0.011 ms	0.378 ± 0.012 ms	0.998 ± 0.043
time_to_load	7.74 ± 0.089 s	7.81 ± 0.011 s	0.991 ± 0.011

Memory benchmarks

	master	56b2b30...	master / 56b2b30...
ODEProblem	0.0375 M allocs: 1.95 MB	0.0375 M allocs: 1.96 MB	0.992
init	0.5 k allocs: 0.0843 MB	0.5 k allocs: 0.0843 MB	1
large_parameter_init/ODEProblem	0.161 M allocs: 6.06 MB	0.161 M allocs: 6.06 MB	1
large_parameter_init/init	0.632 k allocs: 0.178 MB	0.632 k allocs: 0.178 MB	1
mtkcompile	0.0594 M allocs: 3.38 MB	0.0594 M allocs: 3.38 MB	1
sparse_analytical_jacobian/ODEProblem	0.118 M allocs: 5.74 MB	0.118 M allocs: 5.74 MB	1
sparse_analytical_jacobian/f_iip	0 allocs: 0 B	0 allocs: 0 B
sparse_analytical_jacobian/f_oop	0.634 k allocs: 19.6 kB	0.634 k allocs: 19.6 kB	1
time_to_load	0.153 k allocs: 14.5 kB	0.153 k allocs: 14.5 kB	1

[github-actions]

Benchmark Results (Julia v1)

Time benchmarks

	master	56b2b30...	master / 56b2b30...
ODEProblem	5.18 ± 0.26 ms	5.31 ± 0.37 ms	0.975 ± 0.085
init	0.133 ± 0.022 ms	0.132 ± 0.022 ms	1 ± 0.24
large_parameter_init/ODEProblem	14.7 ± 0.76 ms	14.8 ± 1.2 ms	0.992 ± 0.097
large_parameter_init/init	0.141 ± 0.04 ms	0.14 ± 0.04 ms	1.01 ± 0.41
mtkcompile	8.83 ± 0.8 ms	8.96 ± 0.82 ms	0.986 ± 0.13
sparse_analytical_jacobian/ODEProblem	19.8 ± 2.2 ms	19.6 ± 1.5 ms	1.01 ± 0.14
sparse_analytical_jacobian/f_iip	0.06 ± 0.01 μs	0.07 ± 0.001 μs	0.857 ± 0.14
sparse_analytical_jacobian/f_oop	0.108 ± 0.013 ms	0.108 ± 0.012 ms	1 ± 0.16
time_to_load	5.17 ± 0.034 s	5.29 ± 0.025 s	0.978 ± 0.0079

Memory benchmarks

	master	56b2b30...	master / 56b2b30...
ODEProblem	0.0377 M allocs: 1.73 MB	0.0377 M allocs: 1.73 MB	1
init	0.472 k allocs: 0.0602 MB	0.472 k allocs: 0.0602 MB	1
large_parameter_init/ODEProblem	0.157 M allocs: 5.39 MB	0.157 M allocs: 5.39 MB	1
large_parameter_init/init	0.754 k allocs: 0.166 MB	0.754 k allocs: 0.166 MB	1
mtkcompile	0.0557 M allocs: 2.62 MB	0.0557 M allocs: 2.62 MB	1
sparse_analytical_jacobian/ODEProblem	0.118 M allocs: 4.8 MB	0.118 M allocs: 4.8 MB	1
sparse_analytical_jacobian/f_iip	0 allocs: 0 B	0 allocs: 0 B
sparse_analytical_jacobian/f_oop	0.848 k allocs: 27 kB	0.848 k allocs: 27 kB	1
time_to_load	0.201 k allocs: 11.8 kB	0.201 k allocs: 11.8 kB	1