Update render name in tui for approval_policy to match with config values (#1675)

Currently, codex on start shows the value for the approval policy as
name of
[AskForApproval](https://github.com/openai/codex/blob/2437a8d17a0cf972d1a6e7f303d469b6e2f57eae/codex-rs/core/src/protocol.rs#L128)
enum, which differs from
[approval_policy](https://github.com/openai/codex/blob/2437a8d17a0cf972d1a6e7f303d469b6e2f57eae/codex-rs/config.md#approval_policy)
config values.
E.g. "untrusted" becomes "UnlessTrusted", "on-failure" -> "OnFailure",
"never" -> "Never".
This PR changes render names of the approval policy to match with
configuration values.

codex-rs/exec/src/event_processor.rs

@@ -25,7 +25,7 @@ pub(crate) fn create_config_summary_entries(config: &Config) -> Vec<(&'static st
         ("workdir", config.cwd.display().to_string()),
         ("model", config.model.clone()),
         ("provider", config.model_provider_id.clone()),
-        ("approval", format!("{:?}", config.approval_policy)),
+        ("approval", config.approval_policy.to_string()),
         ("sandbox", summarize_sandbox_policy(&config.sandbox_policy)),
     ];
     if config.model_provider.wire_api == WireApi::Responses