[bazel] Improve runfiles handling (#10098)

we can't use runfiles directory on Windows due to path lengths, so swap
to manifest strategy. Parsing the manifest is a bit complex and the
format is changing in Bazel upstream, so pull in the official Rust
library (via a small hack to make it importable...) and cleanup all the
associated logic to work cleanly in both bazel and cargo without extra
confusion

codex-rs/exec/tests/suite/auth_env.rs

@@ -1,5 +1,4 @@
 #![allow(clippy::unwrap_used, clippy::expect_used)]
-use codex_utils_cargo_bin::find_resource;
 use core_test_support::responses::ev_completed;
 use core_test_support::responses::mount_sse_once_match;
 use core_test_support::responses::sse;
@@ -11,7 +10,7 @@ use wiremock::matchers::header;
 async fn exec_uses_codex_api_key_env_var() -> anyhow::Result<()> {
     let test = test_codex_exec();
     let server = start_mock_server().await;
-    let repo_root = find_resource!(".")?;
+    let repo_root = codex_utils_cargo_bin::repo_root()?;
 
     mount_sse_once_match(
         &server,

codex-rs/exec/tests/suite/resume.rs

@@ -113,7 +113,7 @@ fn exec_fixture() -> anyhow::Result<std::path::PathBuf> {
 }
 
 fn exec_repo_root() -> anyhow::Result<std::path::PathBuf> {
-    Ok(find_resource!(".")?)
+    Ok(codex_utils_cargo_bin::repo_root()?)
 }
 
 #[test]