Remove the 'pub' visibility modifier from the Config struct to encapsulate it within the module, preventing external access and improving code organization. This change aligns with best practices for internal data structures that should not be part of the public API.

Add #[cfg(any(feature = "selinux", feature = "smack"))] attributes to Config struct fields
and related code in uumain() to make SELinux/SMACK support optional, preventing compilation
errors when these features are disabled. This improves build flexibility without affecting
core mknod functionality.

- Changed `struct Config<'a>` to `struct Config` to eliminate lifetime parameter
- Updated `context` field from `Option<&'a String>` to `Option<String>` for ownership
- Modified function calls to use `config.context.as_ref()` for borrowing
- Added `.cloned()` when retrieving context from arguments to own the value

This resolves lifetime issues and simplifies the code by avoiding references in the struct.

Reformatted the SMACK label setting block in mknod.rs to remove unnecessary line breaks and indentation, improving readability and aligning with the project's coding style guidelines. No functional changes were made.

…utils into knod_refactoring

Wrap the bitwise OR expression in parentheses and cast to u32 to ensure type consistency and resolve potential compilation issues.

The bitwise OR operation on the file permission flags already yields a u32 value, making the explicit cast unnecessary and improving code clarity.

- Moved `mode_t` to the end of the import list for consistency
- Inlined the `MODE_RW_UGO` constant definition to a single line for brevity
- No functional changes, improves code readability and style

…_UGO

Replace `as u32` casts with `u32::from()` to fix clippy::unnecessary_cast lint warnings, improving code clarity and adhering to Rust best practices. This affects default mode handling in mknod utility.