Scene in memory persistance and debug tools (#24)

![image](https://github.com/storytold/storyteller-bevy/assets/10954133/10eb5c33-2154-4e9d-95ce-1d8e8b822d22)
Debug tools example

---------

Co-authored-by: Danny McGee <dannymcgee@gmail.com>

studio/src/persistance/mod.rs

@@ -0,0 +1,45 @@
+use bevy::prelude::*;
+use space_editor::prelude::*;
+
+pub struct PersistancePlugin;
+
+impl Plugin for PersistancePlugin {
+    fn build(&self, app: &mut App) {
+        info!("PersistancePlugin::build");
+        app.editor_tab_by_trait(
+            EditorTabName::Other("Persistance".to_string()),
+            DebugPersistanceTab::default(),
+        );
+    }
+}
+
+#[derive(Resource, Default)]
+pub struct DebugPersistanceTab {}
+
+impl EditorTab for DebugPersistanceTab {
+    fn ui(
+        &mut self,
+        ui: &mut bevy_inspector_egui::egui::Ui,
+        commands: &mut Commands,
+        world: &mut World,
+    ) {
+        if ui.button("Save").clicked() {
+            world.send_event(EditorEvent::Save(EditorPrefabPath::MemoryCahce));
+        }
+
+        if ui.button("Load").clicked() {
+            world.send_event(EditorEvent::Load(EditorPrefabPath::MemoryCahce));
+        }
+
+        if ui.button("Clear level").clicked() {
+            let mut query = world.query_filtered::<Entity, With<PrefabMarker>>();
+            for e in query.iter(world) {
+                commands.entity(e).despawn_recursive();
+            }
+        }
+    }
+
+    fn title(&self) -> bevy_inspector_egui::egui::WidgetText {
+        "Persistance".into()
+    }
+}