draw a handy dependancy graph

protocols/DEPENDENCIES.md

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+```mermaid
+stateDiagram-v2
+    secp256k1 --> noise_sv2
+    rand --> noise_sv2
+    aes_gcm --> noise_sv2
+    const_sv2 --> noise_sv2
+    rand_chacha --> noise_sv2
+    chacha20poly1305 --> noise_sv2
+
+    serde --> buffer_sv2: with_serde
+    criterion --> buffer_sv2: criterion
+    aes_gcm --> buffer_sv2
+
+    buffer_sv2 --> binary_codec_sv2: with_buffer_pool
+    quickcheck --> binary_codec_sv2: prop_test
+
+    binary_codec_sv2 --> derive_codec_sv2
+
+    serde --> serde_sv2
+    buffer_sv2 --> serde_sv2
+
+    serde_sv2 --> binary_sv2: with_serde
+    serde --> binary_sv2: with_serde
+    binary_codec_sv2 --> binary_sv2: default
+    derive_codec_sv2 --> binary_sv2: default
+    tracing --> binary_sv2
+
+    serde --> framing_sv2: with_serde
+    buffer_sv2 --> framing_sv2: with_buffer_pool
+    binary_sv2 --> framing_sv2
+    const_sv2 --> framing_sv2
+
+    serde --> codec_sv2: with_serde
+    framing_sv2 --> codec_sv2
+    binary_sv2 --> codec_sv2
+    noise_sv2 --> codec_sv2: noise_sv2
+    const_sv2 --> codec_sv2
+    buffer_sv2 --> codec_sv2
+    tracing --> codec_sv2
+```