Split features into codex-features crate (#15253)

- Split the feature system into a new `codex-features` crate.
- Cut `codex-core` and workspace consumers over to the new config and
warning APIs.

Co-authored-by: Ahmed Ibrahim <219906144+aibrahim-oai@users.noreply.github.com>
Co-authored-by: Codex <noreply@openai.com>

codex-rs/core/src/connectors.rs

@@ -33,7 +33,6 @@ use crate::config_loader::AppsRequirementsToml;
 use crate::default_client::create_client;
 use crate::default_client::is_first_party_chat_originator;
 use crate::default_client::originator;
-use crate::features::Feature;
 use crate::mcp::CODEX_APPS_MCP_SERVER_NAME;
 use crate::mcp::McpManager;
 use crate::mcp::ToolPluginProvenance;
@@ -47,6 +46,7 @@ use crate::plugins::list_tool_suggest_discoverable_plugins;
 use crate::token_data::TokenData;
 use crate::tools::discoverable::DiscoverablePluginInfo;
 use crate::tools::discoverable::DiscoverableTool;
+use codex_features::Feature;
 
 pub use codex_connectors::CONNECTORS_CACHE_TTL;
 const CONNECTORS_READY_TIMEOUT_ON_EMPTY_TOOLS: Duration = Duration::from_secs(30);