feat: add LZ77 compression algorithm

Author: AliAlimohammadi

DIRECTORY.md

@@ -57,6 +57,7 @@
     * [XOR](https://github.com/TheAlgorithms/Rust/blob/master/src/ciphers/xor.rs)
   * Compression
     * [Burrows-Wheeler Transform](https://github.com/TheAlgorithms/Rust/blob/master/src/compression/burrows_wheeler_transform.rs)
+    * [LZ77](https://github.com/TheAlgorithms/Rust/blob/master/src/compression/lz77.rs)
     * [Move to Front](https://github.com/TheAlgorithms/Rust/blob/master/src/compression/move_to_front.rs)
     * [Run Length Encoding](https://github.com/TheAlgorithms/Rust/blob/master/src/compression/run_length_encoding.rs)
   * Conversions