Refactor Corrector class to remove unused imports and improve code readability

package edu.bu.LanguageCorrection;

import java.io.BufferedReader;

import java.io.FileReader;

import java.io.IOException;

import java.nio.file.Files;

import java.nio.file.Paths;

import java.io.ByteArrayOutputStream;

import java.io.FileInputStream;

import java.util.List;

import java.util.Map;

import java.util.HashMap;

import java.util.ArrayList;