Tidy up configuration files UNIX permissions (#7983)

* Add missing libpam package causing build to fail using Docker image

```
wrapper.h:1:10: fatal error: 'security/pam_appl.h' file not found
```

Signed-off-by: Samuel FORESTIER <samuel+dev@forestier.app>

* Tidy up configuration files UNIX permissions

Signed-off-by: Samuel FORESTIER <samuel+dev@forestier.app>

---------

Signed-off-by: Samuel FORESTIER <samuel+dev@forestier.app>

libs/hbb_common/src/config.rs

@@ -487,7 +487,19 @@ pub fn load_path<T: serde::Serialize + serde::de::DeserializeOwned + Default + s
 
 #[inline]
 pub fn store_path<T: serde::Serialize>(path: PathBuf, cfg: T) -> crate::ResultType<()> {
-    Ok(confy::store_path(path, cfg)?)
+    #[cfg(not(windows))]
+    {
+        use std::os::unix::fs::PermissionsExt;
+        Ok(confy::store_path_perms(
+            path,
+            cfg,
+            fs::Permissions::from_mode(0o600),
+        )?)
+    }
+    #[cfg(windows)]
+    {
+        Ok(confy::store_path(path, cfg)?)
+    }
 }
 
 impl Config {
@@ -2471,4 +2483,26 @@ mod tests {
             assert_eq!(cfg, Ok(cfg_to_compare), "Failed to test wrong_field_str");
         }
     }
+
+    #[test]
+    fn test_store_load() {
+        let peerconfig_id = "123456789";
+        let cfg: PeerConfig = Default::default();
+        cfg.store(&peerconfig_id);
+        assert_eq!(PeerConfig::load(&peerconfig_id), cfg);
+
+        #[cfg(not(windows))]
+        {
+            use std::os::unix::fs::PermissionsExt;
+            assert_eq!(
+                // ignore file type information by masking with 0o777 (see https://stackoverflow.com/a/50045872)
+                fs::metadata(PeerConfig::path(&peerconfig_id))
+                    .expect("reading metadata failed")
+                    .permissions()
+                    .mode()
+                    & 0o777,
+                0o600
+            );
+        }
+    }
 }