{Core,examples}: add TODO markers for core APIs that require module exposure

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

examples/custom-renderer/Game.zig

@@ -77,6 +77,7 @@ fn tick(
     game: *Mod,
 ) !void {
     // TODO(important): event polling should occur in mach.Core module and get fired as ECS event.
+    // TODO(Core)
     var iter = mach.core.pollEvents();
     var direction = game.state().direction;
     var spawning = game.state().spawning;

examples/custom-renderer/Renderer.zig

@@ -122,10 +122,8 @@ fn tick(
     core: *mach.Core.Mod,
     renderer: *Mod,
 ) !void {
-    const device = core.state().device;
-    _ = device; // autofix
-
     // Grab the back buffer of the swapchain
+    // TODO(Core)
     const back_buffer_view = mach.core.swap_chain.getCurrentTextureView().?;
     defer back_buffer_view.release();