make it actually output the install status and pass the returncode to exec_eval

src/internal/install.rs

@@ -1,9 +1,9 @@
 use std::process::Command;
+use crate::internal::*;
 
 pub fn install(pkgs: Vec<&str>) {
-    Command::new("crystalstrap")
+    exec_eval(Command::new("crystalstrap")
         .arg("/mnt")
-        .args(pkgs)
+        .args(&pkgs)
-        .output()
+        .status(), format!("Install packages {}", pkgs.join(", ")).as_str());
-        .expect("Failed to install packages");
 }