Use runtime authentication for OpenAI MCP and app requests (#59749)

## What changed

- Select fresh authentication for each HTTP operation on eligible OpenAI MCP connections while preserving the connection's credential source and account network policy. Stop redirects when requests carry runtime assertions.
- Pass the owning thread's authentication and runtime context through app discovery, connector metadata, and trusted-access requests. Include the runtime authentication mode in MCP connection and tool-cache identities.
- Give resumed actors analytics clients bound to their own authentication context, and serialize stored-credential reloads with token refresh while preserving host-provided credentials.

## Testing

Add coverage for fresh request assertions, revoked account policies, redirect handling, resumed-actor isolation, and MCP uploads in dual-header and assertion-only modes.

GitOrigin-RevId: f06900a6db61cd6cf53c3aa8075afeec4d5706d9

codex-rs/ext/mcp/src/event_stream_tests.rs

@@ -277,6 +277,7 @@ impl Fixture {
         let startup_cancellation_token = CancellationToken::new();
         let runtime_input = || McpRuntimeInput {
             network_policy_metadata: None,
+            runtime_auth: None,
             startup_policy: McpStartupPolicy::Eager,
             config: Arc::clone(&config),
             plugins_available: false,