feat: implement command execution from user input

src/main.rs

@@ -1,3 +1,13 @@
-fn main() {
-    println!("Hello, world!");
+use std::{io::stdin, process::Command};
+
+fn main(){
+    let mut input = String::new();
+    stdin().read_line(&mut input).unwrap();
+
+    // read_line leaves a trailing newline, which trim removes
+    let command = input.trim(); 
+
+    Command::new(command)
+        .spawn()
+        .unwrap();
 }