fix: use IRStructure for homotopy checking

[AayushSabharwal]

Significantly improves scaling for large models, otherwise ODEProblem can take hours.

Checklist

• Appropriate tests were added
• Any code changes were done in a way that does not break public API
• All documentation related to code changes were updated
• The new code follows the
  contributor guidelines, in particular the SciML Style Guide and
  COLPRAC.
• Any new documentation only uses public API

Additional context

Add any other context about the problem here.

[github-actions]

Benchmark Results (Julia vlts)

Time benchmarks

	master	6be1b77...	master / 6be1b77...
ODEProblem	5.34 ± 0.1 ms	5.43 ± 0.11 ms	0.984 ± 0.027
init	0.0892 ± 0.029 ms	0.0671 ± 0.027 ms	1.33 ± 0.69
large_parameter_init/ODEProblem	20.5 ± 3.8 ms	21.1 ± 4 ms	0.973 ± 0.26
large_parameter_init/init	0.108 ± 0.041 ms	0.09 ± 0.036 ms	1.2 ± 0.66
mtkcompile	9.3 ± 0.56 ms	9.51 ± 0.83 ms	0.978 ± 0.1
sparse_analytical_jacobian/ODEProblem	20.2 ± 0.64 ms	21.1 ± 0.68 ms	0.959 ± 0.043
sparse_analytical_jacobian/f_iip	0.07 ± 0.01 μs	0.07 ± 0.001 μs	1 ± 0.14
sparse_analytical_jacobian/f_oop	0.381 ± 0.011 ms	0.383 ± 0.011 ms	0.995 ± 0.041
time_to_load	5.81 ± 0.013 s	5.9 ± 0.0087 s	0.985 ± 0.0026

Memory benchmarks

	master	6be1b77...	master / 6be1b77...
ODEProblem	0.0376 M allocs: 1.94 MB	0.0376 M allocs: 1.96 MB	0.992
init	0.428 k allocs: 0.0723 MB	0.428 k allocs: 0.0723 MB	1
large_parameter_init/ODEProblem	0.312 M allocs: 11 MB	0.312 M allocs: 11 MB	1
large_parameter_init/init	0.616 k allocs: 0.175 MB	0.616 k allocs: 0.175 MB	1
mtkcompile	0.0617 M allocs: 3.43 MB	0.0617 M allocs: 3.44 MB	0.995
sparse_analytical_jacobian/ODEProblem	0.145 M allocs: 6.55 MB	0.145 M allocs: 6.55 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	6be1b77...	master / 6be1b77...
ODEProblem	5.21 ± 0.56 ms	4.94 ± 0.4 ms	1.06 ± 0.14
init	0.0764 ± 0.01 ms	0.0768 ± 0.0086 ms	0.994 ± 0.17
large_parameter_init/ODEProblem	25.2 ± 4 ms	23.8 ± 3.6 ms	1.06 ± 0.23
large_parameter_init/init	0.0819 ± 0.04 ms	0.0824 ± 0.04 ms	0.995 ± 0.69
mtkcompile	8.76 ± 1.1 ms	8.2 ± 0.49 ms	1.07 ± 0.15
sparse_analytical_jacobian/ODEProblem	19 ± 2 ms	18.8 ± 1.2 ms	1.01 ± 0.13
sparse_analytical_jacobian/f_iip	0.08 ± 0 μs	0.08 ± 0 μs	1 ± 0
sparse_analytical_jacobian/f_oop	0.112 ± 0.013 ms	0.108 ± 0.014 ms	1.04 ± 0.18
time_to_load	5.92 ± 0.1 s	5.55 ± 0.37 s	1.07 ± 0.073

Memory benchmarks

	master	6be1b77...	master / 6be1b77...
ODEProblem	0.0375 M allocs: 1.69 MB	0.0375 M allocs: 1.7 MB	0.991
init	0.426 k allocs: 0.0545 MB	0.426 k allocs: 0.0545 MB	1
large_parameter_init/ODEProblem	0.341 M allocs: 12.3 MB	0.341 M allocs: 12.3 MB	1
large_parameter_init/init	0.809 k allocs: 0.154 MB	0.809 k allocs: 0.154 MB	1
mtkcompile	0.0597 M allocs: 2.74 MB	0.0597 M allocs: 2.74 MB	1
sparse_analytical_jacobian/ODEProblem	0.15 M allocs: 5.93 MB	0.15 M allocs: 5.92 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	0.146 k allocs: 11.4 kB	0.146 k allocs: 11.4 kB	1

[AayushSabharwal]

InterfaceII failures are BVP broken tests now passing. Will fix in a follow-up to avoid holding this back, since it is critical for usability.