tsk-76: Adding function to simplify getting path of Song

src/util/mod.rs

@@ -0,0 +1,13 @@
+pub fn concatenate_path(directory: &str, filename: &str, last_index: usize) -> Result<String, std::io::Error> {
+    if let Some(character) = directory.chars().nth(last_index) {
+        let buffer: String = if character != '/' {
+            format!("{directory}/")
+        } else {
+            String::from(directory)
+        };
+
+        Ok(format!("{buffer}{filename}"))
+    } else {
+        Err(std::io::Error::other(crate::constants::error::LAST_CHARACTER_IN_DIRECTORY))
+    }
+}