fix: resolve Rust compilation errors by fixing imports and missing types

src/compression_engine/lz4.rs

@@ -3,6 +3,9 @@ use log::*;
 use std::io::Write;
 
 use lz4_flex::frame::{FrameDecoder, FrameEncoder};
+use std::fs::File;
+use std::io::{Read, Write};
+use std::path::PathBuf;
 
 use crate::compression_engine::CompressionEngine;