remove mcp-server/src/mcp_protocol.rs and the code that depends on it (#2360)

codex-rs/mcp-server/tests/common/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
+edition = "2024"
 name = "mcp_test_support"
 version = { workspace = true }
-edition = "2024"
 
 [lib]
 path = "lib.rs"
@@ -9,10 +9,11 @@ path = "lib.rs"
 [dependencies]
 anyhow = "1"
 assert_cmd = "2"
-codex-mcp-server = { path = "../.." }
 codex-core = { path = "../../../core" }
+codex-mcp-server = { path = "../.." }
 mcp-types = { path = "../../../mcp-types" }
 pretty_assertions = "1.4.1"
+serde = { version = "1" }
 serde_json = "1"
 shlex = "1.3.0"
 tempfile = "3"
@@ -22,5 +23,5 @@ tokio = { version = "1", features = [
     "process",
     "rt-multi-thread",
 ] }
+uuid = { version = "1", features = ["serde", "v4"] }
 wiremock = "0.6"
-uuid = { version = "1", features = ["serde", "v4"] }