chore: move mcp-server/src/wire_format.rs to protocol/src/mcp_protocol.rs (#2423)

The existing `wire_format.rs` should share more types with the
`codex-protocol` crate (like `AskForApproval` instead of maintaining a
parallel `CodexToolCallApprovalPolicy` enum), so this PR moves
`wire_format.rs` into `codex-protocol`, renaming it as
`mcp-protocol.rs`. We also de-dupe types, where appropriate.

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* #2424
* __->__ #2423

codex-rs/common/Cargo.toml

@@ -9,6 +9,7 @@ workspace = true
 [dependencies]
 clap = { version = "4", features = ["derive", "wrap_help"], optional = true }
 codex-core = { path = "../core" }
+codex-protocol = { path = "../protocol" }
 serde = { version = "1", optional = true }
 toml = { version = "0.9", optional = true }
 

codex-rs/common/src/sandbox_mode_cli_arg.rs

@@ -7,7 +7,7 @@
 //! `config.toml`.
 
 use clap::ValueEnum;
-use codex_core::config_types::SandboxMode;
+use codex_protocol::config_types::SandboxMode;
 
 #[derive(Clone, Copy, Debug, ValueEnum)]
 #[value(rename_all = "kebab-case")]