Remove DPPL ext

[willtebbutt]

Per discussion here -- we're moving the one-liner DynamicPPL extension to DynamicPPL itself, because DynamicPPL now has Mooncake as a versioned test dep.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

[github-actions]

Performance Ratio:
Ratio of time to compute gradient and time to compute function.
Warning: results are very approximate! See here for more context.

┌────────────────────────────┬──────────┬─────────┬─────────────┬─────────┐
│                      Label │ Mooncake │  Zygote │ ReverseDiff │  Enzyme │
│                     String │   String │  String │      String │  String │
├────────────────────────────┼──────────┼─────────┼─────────────┼─────────┤
│                   sum_1000 │     72.4 │     1.0 │        5.61 │ missing │
│                  _sum_1000 │     6.89 │  1200.0 │        33.4 │ missing │
│               sum_sin_1000 │     2.23 │    1.68 │        10.8 │ missing │
│              _sum_sin_1000 │     2.83 │   336.0 │        13.3 │ missing │
│                   kron_sum │     56.1 │    3.43 │       192.0 │ missing │
│              kron_view_sum │     54.1 │    8.42 │       202.0 │ missing │
│      naive_map_sin_cos_exp │     2.53 │ missing │        8.11 │ missing │
│            map_sin_cos_exp │      2.7 │     1.5 │        6.15 │ missing │
│      broadcast_sin_cos_exp │     2.59 │    3.08 │        1.47 │ missing │
│                 simple_mlp │     7.28 │    4.94 │        15.7 │ missing │
│                     gp_lml │     4.47 │    2.26 │     missing │ missing │
│ turing_broadcast_benchmark │     3.07 │ missing │        26.3 │ missing │
│         large_single_block │     4.03 │  3980.0 │        30.1 │ missing │
└────────────────────────────┴──────────┴─────────┴─────────────┴─────────┘