pass active plugins to fomod installer

src/utils.rs

@@ -56,3 +56,10 @@ pub fn walk_all_files(
 
     Ok(a)
 }
+
+pub fn is_plugin_file(filename: impl AsRef<Path>) -> bool {
+    filename
+        .as_ref()
+        .extension()
+        .is_some_and(|ext| ext == "esp" || ext == "esm" || ext == "esl")
+}