[codex][otel] support mtls configuration (#6228)

fix for https://github.com/openai/codex/issues/6153

supports mTLS configuration and includes TLS features in the library
build to enable secure HTTPS connections with custom root certificates.

grpc:
https://docs.rs/tonic/0.13.1/src/tonic/transport/channel/endpoint.rs.html#63
https:
https://docs.rs/reqwest/0.12.23/src/reqwest/async_impl/client.rs.html#516

codex-rs/Cargo.lock

@@ -1366,6 +1366,7 @@ dependencies = [
  "codex-app-server-protocol",
  "codex-protocol",
  "eventsource-stream",
+ "http",
  "opentelemetry",
  "opentelemetry-otlp",
  "opentelemetry-semantic-conventions",
@@ -5174,6 +5175,7 @@ version = "0.23.29"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2491382039b29b9b11ff08b76ff6c97cf287671dbb74f0be44bda389fffe9bd1"
 dependencies = [
+ "log",
  "once_cell",
  "ring",
  "rustls-pki-types",
@@ -6601,8 +6603,10 @@ dependencies = [
  "percent-encoding",
  "pin-project",
  "prost",
+ "rustls-native-certs",
  "socket2 0.5.10",
  "tokio",
+ "tokio-rustls",
  "tokio-stream",
  "tower",
  "tower-layer",