Deterministic peer id from seed for alice

This includes the introduction of the --data-dir parameter instead of the --database.
Both the seed file and the database are stored in the data-dir, the database in sub-folder `database`.

swap/src/fs.rs

@@ -0,0 +1,14 @@
+use std::path::Path;
+
+pub fn ensure_directory_exists(file: &Path) -> Result<(), std::io::Error> {
+    if let Some(path) = file.parent() {
+        if !path.exists() {
+            tracing::info!(
+                "Parent directory does not exist, creating recursively: {}",
+                file.display()
+            );
+            return std::fs::create_dir_all(path);
+        }
+    }
+    Ok(())
+}