Enable --deny-warnings for cargo shear (#21616)

## Summary

In https://github.com/openai/codex/pull/21584, we disabled doctests for
crates that lack any doctests. We can enforce that property via `cargo
shear --deny-warnings`: crates that lack doctests will be flagged if
doctests are enabled, and crates with doctests will be flagged if
doctests are disabled.

A few additional notes:

- By adding `--deny-warnings`, `cargo shear` also flagged a number of
modules that were not reachable at all. Some of those have been removed.
- This PR removes a usage of `windows_modules!` (since `cargo shear` and
`rustfmt` couldn't see through it) in favor of simple `#[cfg(target_os =
"windows")]` macros. As a consequence, many of these files exhibit churn
in this PR, since they weren't being formatted by `rustfmt` at all on
main.
- Again, to make the code more analyzable, this PR also removes some
usages of `#[path = "cwd_junction.rs"]` in favor of a more standard
module structure. The bin sidecar structure is still retained, but,
e.g., `windows-sandbox-rs/src/bin/command_runner.rs‎` was moved to
`windows-sandbox-rs/src/bin/command_runner/main.rs`, and so on.

---------

Co-authored-by: Codex <noreply@openai.com>

codex-rs/windows-sandbox-rs/src/winutil.rs

@@ -3,18 +3,18 @@ use std::ffi::OsStr;
 use std::os::windows::ffi::OsStrExt;
 use windows_sys::Win32::Foundation::ERROR_INSUFFICIENT_BUFFER;
 use windows_sys::Win32::Foundation::GetLastError;
-use windows_sys::Win32::Foundation::LocalFree;
 use windows_sys::Win32::Foundation::HLOCAL;
+use windows_sys::Win32::Foundation::LocalFree;
+use windows_sys::Win32::Security::Authorization::ConvertSidToStringSidW;
 use windows_sys::Win32::Security::Authorization::ConvertStringSidToSidW;
 use windows_sys::Win32::Security::CopySid;
 use windows_sys::Win32::Security::GetLengthSid;
 use windows_sys::Win32::Security::LookupAccountNameW;
 use windows_sys::Win32::Security::SID_NAME_USE;
-use windows_sys::Win32::System::Diagnostics::Debug::FormatMessageW;
 use windows_sys::Win32::System::Diagnostics::Debug::FORMAT_MESSAGE_ALLOCATE_BUFFER;
 use windows_sys::Win32::System::Diagnostics::Debug::FORMAT_MESSAGE_FROM_SYSTEM;
 use windows_sys::Win32::System::Diagnostics::Debug::FORMAT_MESSAGE_IGNORE_INSERTS;
-use windows_sys::Win32::Security::Authorization::ConvertSidToStringSidW;
+use windows_sys::Win32::System::Diagnostics::Debug::FormatMessageW;
 
 pub fn to_wide<S: AsRef<OsStr>>(s: S) -> Vec<u16> {
     let mut v: Vec<u16> = s.as_ref().encode_wide().collect();
@@ -107,7 +107,10 @@ pub fn string_from_sid_bytes(sid: &[u8]) -> Result<String, String> {
         let mut str_ptr: *mut u16 = std::ptr::null_mut();
         let ok = ConvertSidToStringSidW(sid.as_ptr() as *mut std::ffi::c_void, &mut str_ptr);
         if ok == 0 || str_ptr.is_null() {
-            return Err(format!("ConvertSidToStringSidW failed: {}", std::io::Error::last_os_error()));
+            return Err(format!(
+                "ConvertSidToStringSidW failed: {}",
+                std::io::Error::last_os_error()
+            ));
         }
         let mut len = 0;
         while *str_ptr.add(len) != 0 {
@@ -158,7 +161,9 @@ pub fn resolve_sid(name: &str) -> Result<Vec<u8>> {
             domain.resize(domain_len as usize, 0);
             continue;
         }
-        return Err(anyhow::anyhow!("LookupAccountNameW failed for {name}: {err}"));
+        return Err(anyhow::anyhow!(
+            "LookupAccountNameW failed for {name}: {err}"
+        ));
     }
 }