chore: remove once_cell dependency from multiple crates (#4154)

This commit removes the `once_cell` dependency from `Cargo.toml` files
in the `codex-rs` and `apply-patch` directories, replacing its usage
with `std::sync::LazyLock` and `std::sync::OnceLock` where applicable.
This change simplifies the dependency tree and utilizes standard library
features for lazy initialization.

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codex-rs/Cargo.lock

@@ -595,7 +595,6 @@ version = "0.0.0"
 dependencies = [
  "anyhow",
  "assert_cmd",
- "once_cell",
  "pretty_assertions",
  "similar",
  "tempfile",
@@ -956,7 +955,6 @@ dependencies = [
  "lazy_static",
  "libc",
  "mcp-types",
- "once_cell",
  "path-clean",
  "pathdiff",
  "pretty_assertions",