Modernize to Rust 2024 edition and migrate from winapi to windows-sys

[coconutbird]

Summary

Modernizes the entire workspace to Rust 2024 edition and migrates from the legacy winapi crate to windows-sys v0.61.2.

Changes

Dependency migration

• winapi → windows-sys 0.61.2 across dokan-sys, dokan, and the memfs example.
• Replaced all LPCWSTR/LPWSTR type aliases with PCWSTR/PWSTR from windows_sys::core.
• Replaced all locally defined Windows constants (e.g. SECURITY_DESCRIPTOR_REVISION, SEF_AVOID_PRIVILEGE_CHECK, FILE_CASE_PRESERVED_NAMES, etc.) with proper imports from windows-sys.
• Dropped parking_lot dev-dependency — std::sync::Mutex is now competitive on modern Rust (futex-based on Windows since 1.62).
• Replaced lazy_static usage with std::sync::LazyLock (stable since Rust 1.80).

Rust 2024 edition

• Updated all Cargo.toml files to edition = "2024".
• Added unsafe qualifier to extern blocks as required by the new edition.
• Fixed a null pointer dereference in OperationInfo::context() that was always UB but now triggers a non-unwinding panic (abort) in Rust 2024. Added try_context() method with a null check, and updated cleanup/close_file callbacks to handle null context gracefully.

CI

• Added GitHub Actions workflow (.github/workflows/build.yml) that builds and tests on windows-latest.
• Installs the Dokan driver via winget so all tests (including driver-dependent ones) can run.
• Handled std::sync::Mutex poisoning in test harness to prevent cascading failures.
• Fixed test fragility on Windows Server 2025 where the OS issues additional GetFileSecurity queries with unexpected security_information values.

Housekeeping

• Added Cargo.lock to .gitignore.

Testing

All 32 tests pass locally and in CI (Windows). 1 test ignored (can_reset_timeout). Doctests pass.