Verify Safe Rule

[willtebbutt]

I wasn't checking that safe mode can be used with value_and_pullback!! etc. Fortunately, DifferentiationInterface's CI caught the problem. This PR fixes the problem, and ensures that tests are run in safe mode.

[github-actions]

Performance Ratio:

┌────────────────────────────┬────────┬─────────┬─────────────┬─────────┐
│                      Label │  Tapir │  Zygote │ ReverseDiff │  Enzyme │
│                     String │ String │  String │      String │  String │
├────────────────────────────┼────────┼─────────┼─────────────┼─────────┤
│                        sum │   30.4 │   0.324 │        2.34 │   0.479 │
│                       _sum │   6.76 │   484.0 │        27.5 │   0.126 │
│                   kron_sum │   81.7 │    3.34 │       210.0 │    23.5 │
│              kron_view_sum │   96.1 │    11.6 │       244.0 │    8.73 │
│      naive_map_sin_cos_exp │   4.33 │ missing │        8.73 │    2.78 │
│            map_sin_cos_exp │    4.7 │    1.74 │        7.63 │    3.43 │
│      broadcast_sin_cos_exp │   4.35 │    2.62 │        1.69 │    2.88 │
│                 simple_mlp │   12.6 │     3.2 │        11.2 │    3.31 │
│                     gp_lml │   15.7 │    4.06 │     missing │ missing │
│ turing_broadcast_benchmark │   6.35 │ missing │        34.9 │ missing │
└────────────────────────────┴────────┴─────────┴─────────────┴─────────┘