chore(core) Consolidate apply_patch tests (#6545)

## Summary
Consolidates our apply_patch tests into one suite, and ensures each test
case tests the various ways the harness supports apply_patch:
1. Freeform custom tool call
2. JSON function tool
3. Simple shell call
4. Heredoc shell call

There are a few test cases that are specific to a particular variant,
I've left those alone.

## Testing
- [x] This adds a significant number of tests

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

@@ -18,8 +18,6 @@ mod abort_tasks;
 #[cfg(not(target_os = "windows"))]
 mod apply_patch_cli;
 #[cfg(not(target_os = "windows"))]
-mod apply_patch_freeform;
-#[cfg(not(target_os = "windows"))]
 mod approvals;
 mod auth_refresh;
 mod cli_stream;