Kickstart a new rewrite of the raidillon engine

Endless refactors, refactor everyday, refactor relentlessly, refactor
every morning, every day, every hour.

raidillon_platform/src/context.rs

@@ -0,0 +1,11 @@
+use winit::event::Event;
+use crate::AssetManager;
+
+pub struct FrameContext {
+    pub event: Event<()>,
+}
+
+pub struct PlatformContext {
+    pub frame_context: FrameContext,
+    pub asset_manager: dyn AssetManager,
+}