sys: fs: move tests to a sub-module

This ensures that test code is not compiled in regular builds

Signed-off-by: Lukas Wagner <l.wagner@proxmox.com>

proxmox-sys/src/fs/dir.rs

@@ -152,6 +152,10 @@ fn create_path_at_do(
     }
 }
 
+#[cfg(test)]
+mod tests {
+    use super::*;
+
     #[test]
     fn test_create_path() {
         create_path(
@@ -165,3 +169,4 @@ fn test_create_path() {
         )
         .expect("expected create_path to work");
     }
+}