Chemistry equilibrium example

[Transurgeon]

Description

Please include a short summary of the change.
This PR adds an chemistry example.
Issue link (if applicable):

[Transurgeon]

@dance858 maybe I should only make this PR in the dnlp-examples repo?

[github-actions]

Benchmarks that have stayed the same:

   before           after         ratio
 [d147964d]       [cf00928c]
      1.73±0s          1.79±0s     1.04  finance.FactorCovarianceModel.time_compile_problem
      6.55±0s          6.72±0s     1.03  huber_regression.HuberRegression.time_compile_problem
      1.27±0s          1.30±0s     1.02  simple_QP_benchmarks.LeastSquares.time_compile_problem
      308±0ms          314±0ms     1.02  high_dim_convex_plasticity.ConvexPlasticity.time_compile_problem
      1.18±0s          1.20±0s     1.02  simple_LP_benchmarks.SimpleScalarParametrizedLPBenchmark.time_compile_problem
      286±0ms          292±0ms     1.02  simple_QP_benchmarks.SimpleQPBenchmark.time_compile_problem
      422±0ms          430±0ms     1.02  gini_portfolio.Yitzhaki.time_compile_problem
      391±0ms          397±0ms     1.01  slow_pruning_1668_benchmark.SlowPruningBenchmark.time_compile_problem
      20.0±0s          20.2±0s     1.01  finance.CVaRBenchmark.time_compile_problem
      7.79±0s          7.85±0s     1.01  svm_l1_regularization.SVMWithL1Regularization.time_compile_problem
      5.30±0s          5.34±0s     1.01  optimal_advertising.OptimalAdvertising.time_compile_problem
      2.10±0s          2.11±0s     1.01  quantum_hilbert_matrix.QuantumHilbertMatrix.time_compile_problem
      33.9±0s          34.1±0s     1.01  sdp_segfault_1132_benchmark.SDPSegfault1132Benchmark.time_compile_problem
     36.0±0ms         36.1±0ms     1.00  matrix_stuffing.SmallMatrixStuffing.time_compile_problem
      3.10±0s          3.09±0s     1.00  simple_QP_benchmarks.UnconstrainedQP.time_compile_problem
      1.94±0s          1.93±0s     1.00  tv_inpainting.TvInpainting.time_compile_problem
      2.34±0s          2.32±0s     0.99  simple_LP_benchmarks.SimpleFullyParametrizedLPBenchmark.time_compile_problem
      16.3±0s          16.2±0s     0.99  simple_LP_benchmarks.SimpleLPBenchmark.time_compile_problem
      768±0ms          758±0ms     0.99  matrix_stuffing.ConeMatrixStuffingBench.time_compile_problem
      326±0ms          322±0ms     0.99  gini_portfolio.Murray.time_compile_problem
      282±0ms          277±0ms     0.98  matrix_stuffing.ParamSmallMatrixStuffing.time_compile_problem
      569±0ms          558±0ms     0.98  simple_QP_benchmarks.ParametrizedQPBenchmark.time_compile_problem
      951±0ms          930±0ms     0.98  gini_portfolio.Cajas.time_compile_problem
      529±0ms          514±0ms     0.97  semidefinite_programming.SemidefiniteProgramming.time_compile_problem
      1.40±0s          1.34±0s     0.96  matrix_stuffing.ParamConeMatrixStuffing.time_compile_problem

[dance858]

Nice! we can add it here too. But once it's ready, feel free to add it to dnlp-examples.