Handle resuming/forking after compact (#3533)

We need to construct the history different when compact happens. For
this, we need to just consider the history after compact and convert
compact to a response item.

This needs to change and use `build_compact_history` when this #3446 is
merged.

codex-rs/core/tests/suite/mod.rs

@@ -3,6 +3,7 @@
 mod cli_stream;
 mod client;
 mod compact;
+mod compact_resume_fork;
 mod exec;
 mod exec_stream_events;
 mod fork_conversation;