Implement full-duplex secret connection

.changelog/unreleased/improvements/814-clonable-secret-conn.md

@@ -0,0 +1,4 @@
+- `[tendermint-p2p]` The `SecretConnection` can now be split into two halves to
+  facilitate full-duplex communication (must be facilitated by using each half
+  in a separate thread).
+  ([#938](https://github.com/informalsystems/tendermint-rs/pull/938))

Cargo.toml

@@ -8,6 +8,7 @@ members = [
     "pbt-gen",
     "proto",
     "rpc",
+    "std-ext",
     "tendermint",
     "test",
     "testgen"

p2p/Cargo.toml

@@ -43,6 +43,7 @@ zeroize = "1"
 # path dependencies
 tendermint = { path = "../tendermint", version = "0.21.0" }
 tendermint-proto = { path = "../proto", version = "0.21.0" }
+tendermint-std-ext = { path = "../std-ext", version = "0.21.0" }
 
 # optional dependencies
 prost-amino = { version = "0.6", optional = true }