Function load_cache 

pub fn load_cache(
    path: &PathBuf,
    current_signature: &[String],
) -> Option<Vec<ServiceImpact>>

What: Load cached service impact data when the stored signature matches the current list.

Inputs:

• path: Filesystem location of the serialized ServiceCache JSON.
• current_signature: Signature derived from the current install list for validation.

Output:

• Some(Vec<ServiceImpact>) when the cache exists, deserializes, and signatures agree; None otherwise.

Details:

• Reads the JSON, deserializes it, sorts both signatures, and compares them before returning the cached service impact data.